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作业调度是处理机的高级调度,进程调度是处理机的低级调度。
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作业调度选择一个作业装入主存后该作业能否占用处理机须由______来决定
设备管理
作业控制
驱动调度
进程调度
进程调度算法解决以何种次序对各就绪进程进行处理机的分配以及按何种时间比例让进程占用处理机时间片轮转进
处理机调度包括高级调度________中级调度或中程调度
__调度是处理机的高级调度__调度是处理机的低级调度
操作系统中的管理部分负责对作业和进程进行调度对系统中的信息资源进行管理的叫做管理 操作系统中
处理机
存储
文件
设备
所谓进程调度就是采用某种算法合理有效地把处理机分配给进程
处理机调度可分为三级高级中级和低级在所有的系统中都必须 具备这三级调度
关于处理机调度试问1什么是处理机三级调度2处理机三级调度分别在什么情况下发生3各级调度分别完成什么工
关于处理机调度试问 1什么是处理机三级调度? 2处理机三级调度分别在什么情况下发生? 3各级调度分
若系统中只有用户级线程则处理机调度单位是
线程
进程
程序
作业
下列关于进程调度的说法17是错误的
进程调度的任务是控制、协调进程对CPU的竞争,进程调度即处理机调度
调度算法解决以什么次序、按何种时间比例对就绪进程分配处理机
时间片轮转法中,时间片长度的选取并不重要
进程优先级的设置可以是静态的,也可以是动态的
下面的叙述中正确的是______
进程获得处理机运行是通过调度得到的
优先级是进程调度的重要依据,一旦确定不能改动
在单处理机的系统中,任何时刻都只有一个进程处于运行状态
进程申请处理机而得不到满足时,其状态变为阻塞
操作系统中的三级调度是
处理机调度、资源调度和网络调度
处理机调度、内外存调度和作业调度
处理机调度、内外存调度和负载均衡调度
处理机调度、设备调度和作业调度
在__调度算法中按照进程进入就绪队列的先后次序来分配处理机
进程是程序的一次执行是抢占处理机的调度单位
处理机调度一般可分为三级其中调度必不可少
下列关于进程调度的说法7是错误的
进程调度的任务是控制、协调进程对CPU的竞争,进程调度即处理机调度
调度算法解决以什么次序、按何种时间比例对就绪进程分配处理机
时间片轮转法中,时间片长度的选取并不重要
进程优先级的设置可以是静态的,也可以是动态的
从调度所实现的功能来分处理机调度一般可分为作业调度内存挂起与对换和三级
操作系统中负责对进程进行调度
处理机管理
作业管理
高级调度管理
存储和设备管理
若某单处理器多进程系统中有多个就绪态进程则下列关于处理机调度的叙述中错误的是
在进程结束时能进行处理机调度
创建新进程后能进行处理机调度
在进程处于临界区时不能进行处理机调度
在系统调用完成并返回用户态时能进行处理机调度
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Directions: Achemicalplantshouldberesponsibleforthewaterpollutioninanearbyriver.WritealettertotheCityEnvironmentProtectionAgencyto 注投诉信是应用文命题的重点之一 1statethepresentsituation 2suggestwaystodealwiththeproblemand 3expressyoursincerehope.Youshouldwriteabout100wordsonANSWERSHEET2. Donotsignyourownnameattheendoftheletter.Use"LiMing"instead. Donotneedtowritetheaddress.
PrinceKlemensVonMetternichforeignministeroftheAustrianEmpireduringtheNapoleoniceraanditsaftermathwouldhavenotroublerecognizingGoogle.Tohimtheworld’smostpopularweb-searchenginewouldcloselyresembletheNapoleonicFrancethatinhisyouthhumiliatedAustriaandEurope’sotherpowers.Itsrivals—Yahoo!thelargestofthetraditionalwebgatewayseBaythebiggestonlineauctionandtradingsiteandMicrosoftasoftwareempirethatownsMSNastrugglingwebportal—wouldlookalotlikeRussiaPrussiaandAustria.Metternichrespondedbyforginganallianceamongthosethreemonarchiestocreatea"balanceofpower"againstFrance.Google’senemieshemightsayoughtnowtodothesamething. GoogleannouncedtwonewconquestsonAugust7th.ItstruckadealwithViacoman"old"mediafirmunderwhichitwillsyndicatevideoclipsfromViacombrandssuchasMTVandNickelodeontootherwebsitesandintegrateadvertisementsintothem.ThismakesGoogletheclearleaderinthefledglingbutpromisingmarketforweb-videoadvertising.ItalsoannouncedadealwithNewsCorporationanothermediagiantunderwhichitwillpro-videallthesearchandtext-advertisingtechnologyonNewsCorporation’swebsitesincludingMySpaceanenormouslypopularsocial-networkingsite. ThesearehardblowsforYahoo!andMSNwhichhadalsobeennegotiatingwithNewsCorporation.BothfirmshavebeenlosingmarketshareinwebsearchtoGoogleoverthepastyear—Googlenowhashalfthemarket.TheyhavealsofallenfurtherbehindintheiradvertisingtechnologiesandnetworkssothatbothmakelessmoneythanGoogledoesfromthesamenumberofsearches.SafaRashtchyananalystatPiperJaffrayasecuritiesfirmestimatesthatforeveryadvertisingdollarthatGooglemakesonasearchqueryYahoo!makesonly60-70cents.LastmonthYahoo!saidthatanewadvertisingalgorithmthatithaddesignedtoclosethegapinprofitabilitywillbedelayedanditssharepricefellby22%itsbiggest-everone-daydrop. MSNisfurtherbehindGooglethanYahoo!insearchanditsparentMicrosoftfacesanevenmorefundamentalthreatfromtheexpansionistnewpower.ManyofGoogle’snewventuresbeyondwebsearchenableuserstodothingsfreeofchargethroughtheirwebbrowsersthattheynowdousingMicrosoftsoftwareontheirpersonalcomputers.Googleoffersarudimentarybutfreeonlinewordprocessorandspreadsheetforinstance. ThesmallereBayontheotherhandmightinonesenseclaimGoogleasanally.Google’ssearchresultssendalotoftraffictoeBay’sauctionsiteandeBayisoneofthebiggestadvertisersonGoogle’snetwork.Buttherelationshipisimbalanced.Aninfluentialre-centstudyfromBerkeley’sHaasSchoolofBusinessestimatedthatabout12%ofeBay’srevenuescomeindirectlyfromGooglewhereasGooglegetsonly3%ofitsrevenuesfromeBay.WorstofallforeBayGoogleisstartingtoundercutitscorebusiness.SellersaresettinguptheirownwebsitesandbuyingtextadvertisementsfromGoogleandbuyersareusingitssearchratherthaneBaytoconnectwithsellersdirectly.Asaresult"eBaywouldbewisetostrikeadeeppartnershipwithYahoo!orMicrosoftinordertoregainabalanceofpowerintheindustry"saidthestudy’sauthorsJulienDecotandSteveLeesoundinglikediplomatsattheCongressofViennain1814. PrinceKlemensismentionedinthefirstparagraphto
PrinceKlemensVonMetternichforeignministeroftheAustrianEmpireduringtheNapoleoniceraanditsaftermathwouldhavenotroublerecognizingGoogle.Tohimtheworld’smostpopularweb-searchenginewouldcloselyresembletheNapoleonicFrancethatinhisyouthhumiliatedAustriaandEurope’sotherpowers.Itsrivals—Yahoo!thelargestofthetraditionalwebgatewayseBaythebiggestonlineauctionandtradingsiteandMicrosoftasoftwareempirethatownsMSNastrugglingwebportal—wouldlookalotlikeRussiaPrussiaandAustria.Metternichrespondedbyforginganallianceamongthosethreemonarchiestocreatea"balanceofpower"againstFrance.Google’senemieshemightsayoughtnowtodothesamething. GoogleannouncedtwonewconquestsonAugust7th.ItstruckadealwithViacoman"old"mediafirmunderwhichitwillsyndicatevideoclipsfromViacombrandssuchasMTVandNickelodeontootherwebsitesandintegrateadvertisementsintothem.ThismakesGoogletheclearleaderinthefledglingbutpromisingmarketforweb-videoadvertising.ItalsoannouncedadealwithNewsCorporationanothermediagiantunderwhichitwillpro-videallthesearchandtext-advertisingtechnologyonNewsCorporation’swebsitesincludingMySpaceanenormouslypopularsocial-networkingsite. ThesearehardblowsforYahoo!andMSNwhichhadalsobeennegotiatingwithNewsCorporation.BothfirmshavebeenlosingmarketshareinwebsearchtoGoogleoverthepastyear—Googlenowhashalfthemarket.TheyhavealsofallenfurtherbehindintheiradvertisingtechnologiesandnetworkssothatbothmakelessmoneythanGoogledoesfromthesamenumberofsearches.SafaRashtchyananalystatPiperJaffrayasecuritiesfirmestimatesthatforeveryadvertisingdollarthatGooglemakesonasearchqueryYahoo!makesonly60-70cents.LastmonthYahoo!saidthatanewadvertisingalgorithmthatithaddesignedtoclosethegapinprofitabilitywillbedelayedanditssharepricefellby22%itsbiggest-everone-daydrop. MSNisfurtherbehindGooglethanYahoo!insearchanditsparentMicrosoftfacesanevenmorefundamentalthreatfromtheexpansionistnewpower.ManyofGoogle’snewventuresbeyondwebsearchenableuserstodothingsfreeofchargethroughtheirwebbrowsersthattheynowdousingMicrosoftsoftwareontheirpersonalcomputers.Googleoffersarudimentarybutfreeonlinewordprocessorandspreadsheetforinstance. ThesmallereBayontheotherhandmightinonesenseclaimGoogleasanally.Google’ssearchresultssendalotoftraffictoeBay’sauctionsiteandeBayisoneofthebiggestadvertisersonGoogle’snetwork.Buttherelationshipisimbalanced.Aninfluentialre-centstudyfromBerkeley’sHaasSchoolofBusinessestimatedthatabout12%ofeBay’srevenuescomeindirectlyfromGooglewhereasGooglegetsonly3%ofitsrevenuesfromeBay.WorstofallforeBayGoogleisstartingtoundercutitscorebusiness.SellersaresettinguptheirownwebsitesandbuyingtextadvertisementsfromGoogleandbuyersareusingitssearchratherthaneBaytoconnectwithsellersdirectly.Asaresult"eBaywouldbewisetostrikeadeeppartnershipwithYahoo!orMicrosoftinordertoregainabalanceofpowerintheindustry"saidthestudy’sauthorsJulienDecotandSteveLeesoundinglikediplomatsattheCongressofViennain1814. Yahoo!andMSNaremakinglessmoneyforthesamenumberofsearcheschieflybecause
PrinceKlemensVonMetternichforeignministeroftheAustrianEmpireduringtheNapoleoniceraanditsaftermathwouldhavenotroublerecognizingGoogle.Tohimtheworld’smostpopularweb-searchenginewouldcloselyresembletheNapoleonicFrancethatinhisyouthhumiliatedAustriaandEurope’sotherpowers.Itsrivals—Yahoo!thelargestofthetraditionalwebgatewayseBaythebiggestonlineauctionandtradingsiteandMicrosoftasoftwareempirethatownsMSNastrugglingwebportal—wouldlookalotlikeRussiaPrussiaandAustria.Metternichrespondedbyforginganallianceamongthosethreemonarchiestocreatea"balanceofpower"againstFrance.Google’senemieshemightsayoughtnowtodothesamething. GoogleannouncedtwonewconquestsonAugust7th.ItstruckadealwithViacoman"old"mediafirmunderwhichitwillsyndicatevideoclipsfromViacombrandssuchasMTVandNickelodeontootherwebsitesandintegrateadvertisementsintothem.ThismakesGoogletheclearleaderinthefledglingbutpromisingmarketforweb-videoadvertising.ItalsoannouncedadealwithNewsCorporationanothermediagiantunderwhichitwillpro-videallthesearchandtext-advertisingtechnologyonNewsCorporation’swebsitesincludingMySpaceanenormouslypopularsocial-networkingsite. ThesearehardblowsforYahoo!andMSNwhichhadalsobeennegotiatingwithNewsCorporation.BothfirmshavebeenlosingmarketshareinwebsearchtoGoogleoverthepastyear—Googlenowhashalfthemarket.TheyhavealsofallenfurtherbehindintheiradvertisingtechnologiesandnetworkssothatbothmakelessmoneythanGoogledoesfromthesamenumberofsearches.SafaRashtchyananalystatPiperJaffrayasecuritiesfirmestimatesthatforeveryadvertisingdollarthatGooglemakesonasearchqueryYahoo!makesonly60-70cents.LastmonthYahoo!saidthatanewadvertisingalgorithmthatithaddesignedtoclosethegapinprofitabilitywillbedelayedanditssharepricefellby22%itsbiggest-everone-daydrop. MSNisfurtherbehindGooglethanYahoo!insearchanditsparentMicrosoftfacesanevenmorefundamentalthreatfromtheexpansionistnewpower.ManyofGoogle’snewventuresbeyondwebsearchenableuserstodothingsfreeofchargethroughtheirwebbrowsersthattheynowdousingMicrosoftsoftwareontheirpersonalcomputers.Googleoffersarudimentarybutfreeonlinewordprocessorandspreadsheetforinstance. ThesmallereBayontheotherhandmightinonesenseclaimGoogleasanally.Google’ssearchresultssendalotoftraffictoeBay’sauctionsiteandeBayisoneofthebiggestadvertisersonGoogle’snetwork.Buttherelationshipisimbalanced.Aninfluentialre-centstudyfromBerkeley’sHaasSchoolofBusinessestimatedthatabout12%ofeBay’srevenuescomeindirectlyfromGooglewhereasGooglegetsonly3%ofitsrevenuesfromeBay.WorstofallforeBayGoogleisstartingtoundercutitscorebusiness.SellersaresettinguptheirownwebsitesandbuyingtextadvertisementsfromGoogleandbuyersareusingitssearchratherthaneBaytoconnectwithsellersdirectly.Asaresult"eBaywouldbewisetostrikeadeeppartnershipwithYahoo!orMicrosoftinordertoregainabalanceofpowerintheindustry"saidthestudy’sauthorsJulienDecotandSteveLeesoundinglikediplomatsattheCongressofViennain1814. JulienandSteveseemtosuggestthat
FewpeoplewoulddefendtheVictorianattitudetochildrenbutifyouwereaparentinthosedaysatleastyouknewwhereyoustood:childrenweretobeseenandnotheard.Freudandhiscompanydidawaywithallthatandparentshavebeenbewilderedeversince.Thechild’shappinessisall-importantthepsychologistssaybutwhatabouttheparents’happinessParentssuffercontinuallyfromfearandguiltwhiletheirchildrengailyrompaboutpullingtheplaceapart.Agood"old-fashioned"spankingisoutofthequestion:nomodernchild-rearingmanualwouldpermitsuchbarbarity.Thetroubleisyouarenotallowedeventoshout.WhoknowswhatdeeppsychologicalwoundsyoumightinflictThepoorchildmayneverrecoverfromthedreadfultraumaticexperience.Soitisthatparentsbendoverbackwardstoavoidgivingtheirchildrencomplexeswhichahundredyearsagohadn’tevenbeenheardof.Certainlyachildneedsloveandalotofit.Buttheexcessivepermissivenessofmodernparentsissurelydoingmoreharmthangood. Psychologistshavesucceededinunderminingparents’confidenceintheirownauthority.Andithasn’ttakenchildrenlongtogetwindofthefact.Inadditiontothegreatmodernclassicsonchild-caretherearecountlessarticlesinmagazinesandnewspapers.Withsomuchunsolicitedadviceflyingaboutmumanddadjustdon’tknowwhattodoanymore.Intheendtheydonothingatall.Sofromearlychildhoodthekidsareinchargeandparents’livesareregulatedaccordingtotheneedsoftheiroffspring.Whenthelittledearsdevelopintoteenagerstheytakecompletecontrol.Laxauthorityovertheyearsmakesadolescentrebellionagainstparentsallthemoreviolent.Iftheyoungpeoplearegoingtohaveapartyforinstanceparentsareaskedtoleavethehouse.Theirpresencemerelyspoilsthefun.Whatelsecanthepoorparentsdobutobey Childrenarehardycreaturesfarhardierthanthepsychologistswouldhaveusbelieveandmostofthemsurvivetheharmfulinfluenceofextremepermissivenesswhichisthenormalconditioninthemodernhousehold.Butagreatmanydonot.Thespreadofjuveniledelinquencyinourownageislargelyduetoparentallaxity.MotherbelievingthatlittleJohnnycanlookafterhimselfisnotathomewhenhereturnsfromschoolsolittleJohnnyroamsthestreets.Thedividing-linebetweenpermissivenessandsheernegligenceisveryfineindeed. Thepsychologistshavemuchtoanswerfor.Theyshouldkeeptheirmouthsshutandletparentsgetonwiththejob.Andifchildrenareknockedaboutalittlebitintheprocessitmaynotreallymattertoomuch.Atleastthiswillhelpthemtodevelopvigorousviewsoftheirownandgivethemsomethingpositivetoreactagainst.Perhapsthere’ssometruthintheideathatchildrenwhohavehadasurfeitofhappinessin.theirchildhoodappearlikestodgypuddingsandfail.tomakeasuccessoflife. WhatdoestheauthorwantstoillustratewithJohnnyroamingthestreets
管道通信的基本思想是什么UNIX操作系统在管道通信中是如何避免死锁的
FewpeoplewoulddefendtheVictorianattitudetochildrenbutifyouwereaparentinthosedaysatleastyouknewwhereyoustood:childrenweretobeseenandnotheard.Freudandhiscompanydidawaywithallthatandparentshavebeenbewilderedeversince.Thechild’shappinessisall-importantthepsychologistssaybutwhatabouttheparents’happinessParentssuffercontinuallyfromfearandguiltwhiletheirchildrengailyrompaboutpullingtheplaceapart.Agood"old-fashioned"spankingisoutofthequestion:nomodernchild-rearingmanualwouldpermitsuchbarbarity.Thetroubleisyouarenotallowedeventoshout.WhoknowswhatdeeppsychologicalwoundsyoumightinflictThepoorchildmayneverrecoverfromthedreadfultraumaticexperience.Soitisthatparentsbendoverbackwardstoavoidgivingtheirchildrencomplexeswhichahundredyearsagohadn’tevenbeenheardof.Certainlyachildneedsloveandalotofit.Buttheexcessivepermissivenessofmodernparentsissurelydoingmoreharmthangood. Psychologistshavesucceededinunderminingparents’confidenceintheirownauthority.Andithasn’ttakenchildrenlongtogetwindofthefact.Inadditiontothegreatmodernclassicsonchild-caretherearecountlessarticlesinmagazinesandnewspapers.Withsomuchunsolicitedadviceflyingaboutmumanddadjustdon’tknowwhattodoanymore.Intheendtheydonothingatall.Sofromearlychildhoodthekidsareinchargeandparents’livesareregulatedaccordingtotheneedsoftheiroffspring.Whenthelittledearsdevelopintoteenagerstheytakecompletecontrol.Laxauthorityovertheyearsmakesadolescentrebellionagainstparentsallthemoreviolent.Iftheyoungpeoplearegoingtohaveapartyforinstanceparentsareaskedtoleavethehouse.Theirpresencemerelyspoilsthefun.Whatelsecanthepoorparentsdobutobey Childrenarehardycreaturesfarhardierthanthepsychologistswouldhaveusbelieveandmostofthemsurvivetheharmfulinfluenceofextremepermissivenesswhichisthenormalconditioninthemodernhousehold.Butagreatmanydonot.Thespreadofjuveniledelinquencyinourownageislargelyduetoparentallaxity.MotherbelievingthatlittleJohnnycanlookafterhimselfisnotathomewhenhereturnsfromschoolsolittleJohnnyroamsthestreets.Thedividing-linebetweenpermissivenessandsheernegligenceisveryfineindeed. Thepsychologistshavemuchtoanswerfor.Theyshouldkeeptheirmouthsshutandletparentsgetonwiththejob.Andifchildrenareknockedaboutalittlebitintheprocessitmaynotreallymattertoomuch.Atleastthiswillhelpthemtodevelopvigorousviewsoftheirownandgivethemsomethingpositivetoreactagainst.Perhapsthere’ssometruthintheideathatchildrenwhohavehadasurfeitofhappinessin.theirchildhoodappearlikestodgypuddingsandfail.tomakeasuccessoflife. Itseemsthattheauthorismostcriticalof
[A]Convenientpackaging [B]Healthandwellness [C]Skepticalcustomers [D]Enormousmarkets [E]Soaringsales [F]Trendydrink Inthelast40yearsthebottledwaterindustryhasgonefromabusinessprospectthatfewtookseriouslytoaglobalindustryworthbillionsofpounds.Thecommodityitselfremainssimple.Thewaywethinkaboutithaschangedfundamentally.Waterisnaturalpureandsourcedatminimalcost.Itsrealvalueliesinitsmarketingandbranding."Ithinkbottledwateristhemostrevealingsubstanceforshowingushowtheglobalcapitalistmarketworkstoday"saysRichardWilkprofessorofanthropologyatIndianaUniversity."Inasensewe’rebuyingchoicewe’rebuyingfreedom.That’stheonlythingthatcanexplainwhyyouwouldpaymoneyforabottleofsomethingthatyoucanotherwisegetforfree." 41.______ Throughaconfectionofadvertisingandmarketingbottledwaterhasbecomeoneofthebiggestsuccessstoriesinthemodernfoodandbeverageindustry."Thedemandforbottlewaterhasgrownexponentiallyinthelastfewdecades"saysDr.PeterGleickauthorofBottledandSold."It’sdoubledit’sdoubledagainandit’sdoubledagain.Andthebottlewatercompaniesseeenormousmarketsnotjustintherichcountriesbutalsointhepoorercountries." Noactualvariety Somepeoplethinkthatbottledwateristhehighpointofglobalcapitalismparticularlythepeopleinthebottledwaterbusiness."Ithinkbottledwateractuallyrepresentsakindofcaricatureoftheglobaleconomy.Itprovidespeopleinthedevelopedworldwith20or30varietiesofsomethingforwhichthereisnoactualvariety"saysCharlesFishmanauthorofTheBigThirst. 42.______. Atthebeginningtherereallywasnovarietyandthebottledwaterphenomenonbeganwithonebrand.Perrier佩绿雅矿泉水品牌wasatriumphofadvertisingcreatingabrandthatwastodefineageneration.AttheheartofthecampaigntomakethebrandpopularwasRichardWheatleyoftheLeoBurnettadvertisingagencybetween1979and1994."Perrierpopularisedbottledwater"hesays."Itmadeitacceptablemorethanacceptableitmadeit...desirable."Butitwasnotaninstantsuccess.WhenPerrierUKwaslookingtoincreaseitssalesintheearly1970’sitfacedaskepticalpublic.Manyquestionedwhyanyonewouldbuywaterwhenyoucouldgetitfreefromthetap. 43.______. FacedwithobstaclesPerrierturnedtoadvertisingwithacampaignthatwastochangeourconsumerlandscapeforever.Thecampaignwasamarketingcoupandsaleswentthroughtherooffrom12millionbottlesin1980to152millionbytheendofthedecade.Perrierwasnolongerjustabottleofwater.Themarketingandadvertisingteamshadestablishedacrucialemotionallinkbetweentheproductandtheconsumers."Perrierbecameabadge"saysMichaelBellaschairmanoftheBeverageMarketingCorporation."WhenyouheldaPerrierbottleupitsaidsomethingaboutyourselfitsaidyouweresophisticatedyouunderstoodwhatwashappeningintheworld.Itwasaperfectbeveragefortheyoungandcomingbusinessexecutivesthetrend-setters." 44.______. Inanageofinstantgratificationstillwaterinportablebottlesprovidedwhatpeopleneededexactlywhentheyneededit."Peopleingeneralaremoreandmoretimepressed"saysMr.Fishman."Wedon’tcookourownmealsanymoreweeatpreparedfoodsofallkinds.Andthere’snothingmoreappealingthanabottleofcoldwateratamomentwhenyou’rereallythirsty.ButIthinkbottledwaterisoneofthoseproductsthatonmanyoccasionswhenpeoplebuyitwhatthey’rebuyingisn’tthewatersomuchasthebottle.Thatisthepackageandtheconvenienceatthatmoment." 45.______. WhenpeopleboughtthisconveniencewhattheywerereallybuyingwasPolyethyleneTerephthalateorPETthesinglemostimportantinnovationintheindustry’shistory.StrongshatterproofandahighlyvaluedformofpolyesterPETisaby-productoftheoilindustry.Itisnowutilisedinthepackagingofeverythingfrompharmaceuticalsandsoaptoreadymeals.InyearstocometheenvironmentalimpactofPETwouldhaunttheindustryandraisequestionsaboutitsverysurvivalbutinthe1990sthiswasarevolution.AccordingtoMr.Bellasitwasbehindthesubsequentincrediblegrowthoftheindustry."StartingwiththeintroductionofthesmallpremiumPETwatersthecategorystartedtoexplode"saysMr.Bellas."ThebottledwaterindustrybeforePETonthelistofallbeveragecategorieswasnumberseven.WiththeadventofPETwaterjumpedtothenumbertwospotbehindcarbonatedsoftdrinks." Bybrandingandmarketingwaterbottledwaterhasbeentransformedfromsomethingthatmanyofustookforgrantedintoaproductthatnowmakesbillionsforglobalmultinationalcompanies. 45
某分时系统中的进程可能出现如图2-13所示的状态变化回答下列问题 把图2-13中的每一个状态变化的原因填在表2-8相应的栏中
著名的哲学家就餐问题是指五位哲学家围圆桌就座桌上每二人之间放一根筷子任一位哲学家修学中饿了便可且只能拿起左右两边的筷子吃饭餐后将两根筷子各放回原处自己也继续做学问如此往复即对哲学家Pii=01234有循环进程SiPi做学问Pi取左手的i号筷子和右手的i+1rood5号筷子Pi就餐Pi将两根筷子分放回原处哲学家就餐问题是这样5个进程组成的系统请分别用死锁预防死锁避免死锁检测与恢复改造系统
消息缓冲通信技术是一种高级通信机制由Hansen首先提出请回答下列问题给出消息缓冲机制有限缓冲的基本工作原理
[A]Convenientpackaging [B]Healthandwellness [C]Skepticalcustomers [D]Enormousmarkets [E]Soaringsales [F]Trendydrink Inthelast40yearsthebottledwaterindustryhasgonefromabusinessprospectthatfewtookseriouslytoaglobalindustryworthbillionsofpounds.Thecommodityitselfremainssimple.Thewaywethinkaboutithaschangedfundamentally.Waterisnaturalpureandsourcedatminimalcost.Itsrealvalueliesinitsmarketingandbranding."Ithinkbottledwateristhemostrevealingsubstanceforshowingushowtheglobalcapitalistmarketworkstoday"saysRichardWilkprofessorofanthropologyatIndianaUniversity."Inasensewe’rebuyingchoicewe’rebuyingfreedom.That’stheonlythingthatcanexplainwhyyouwouldpaymoneyforabottleofsomethingthatyoucanotherwisegetforfree." 41.______ Throughaconfectionofadvertisingandmarketingbottledwaterhasbecomeoneofthebiggestsuccessstoriesinthemodernfoodandbeverageindustry."Thedemandforbottlewaterhasgrownexponentiallyinthelastfewdecades"saysDr.PeterGleickauthorofBottledandSold."It’sdoubledit’sdoubledagainandit’sdoubledagain.Andthebottlewatercompaniesseeenormousmarketsnotjustintherichcountriesbutalsointhepoorercountries." Noactualvariety Somepeoplethinkthatbottledwateristhehighpointofglobalcapitalismparticularlythepeopleinthebottledwaterbusiness."Ithinkbottledwateractuallyrepresentsakindofcaricatureoftheglobaleconomy.Itprovidespeopleinthedevelopedworldwith20or30varietiesofsomethingforwhichthereisnoactualvariety"saysCharlesFishmanauthorofTheBigThirst. 42.______. Atthebeginningtherereallywasnovarietyandthebottledwaterphenomenonbeganwithonebrand.Perrier佩绿雅矿泉水品牌wasatriumphofadvertisingcreatingabrandthatwastodefineageneration.AttheheartofthecampaigntomakethebrandpopularwasRichardWheatleyoftheLeoBurnettadvertisingagencybetween1979and1994."Perrierpopularisedbottledwater"hesays."Itmadeitacceptablemorethanacceptableitmadeit...desirable."Butitwasnotaninstantsuccess.WhenPerrierUKwaslookingtoincreaseitssalesintheearly1970’sitfacedaskepticalpublic.Manyquestionedwhyanyonewouldbuywaterwhenyoucouldgetitfreefromthetap. 43.______. FacedwithobstaclesPerrierturnedtoadvertisingwithacampaignthatwastochangeourconsumerlandscapeforever.Thecampaignwasamarketingcoupandsaleswentthroughtherooffrom12millionbottlesin1980to152millionbytheendofthedecade.Perrierwasnolongerjustabottleofwater.Themarketingandadvertisingteamshadestablishedacrucialemotionallinkbetweentheproductandtheconsumers."Perrierbecameabadge"saysMichaelBellaschairmanoftheBeverageMarketingCorporation."WhenyouheldaPerrierbottleupitsaidsomethingaboutyourselfitsaidyouweresophisticatedyouunderstoodwhatwashappeningintheworld.Itwasaperfectbeveragefortheyoungandcomingbusinessexecutivesthetrend-setters." 44.______. Inanageofinstantgratificationstillwaterinportablebottlesprovidedwhatpeopleneededexactlywhentheyneededit."Peopleingeneralaremoreandmoretimepressed"saysMr.Fishman."Wedon’tcookourownmealsanymoreweeatpreparedfoodsofallkinds.Andthere’snothingmoreappealingthanabottleofcoldwateratamomentwhenyou’rereallythirsty.ButIthinkbottledwaterisoneofthoseproductsthatonmanyoccasionswhenpeoplebuyitwhatthey’rebuyingisn’tthewatersomuchasthebottle.Thatisthepackageandtheconvenienceatthatmoment." 45.______. WhenpeopleboughtthisconveniencewhattheywerereallybuyingwasPolyethyleneTerephthalateorPETthesinglemostimportantinnovationintheindustry’shistory.StrongshatterproofandahighlyvaluedformofpolyesterPETisaby-productoftheoilindustry.Itisnowutilisedinthepackagingofeverythingfrompharmaceuticalsandsoaptoreadymeals.InyearstocometheenvironmentalimpactofPETwouldhaunttheindustryandraisequestionsaboutitsverysurvivalbutinthe1990sthiswasarevolution.AccordingtoMr.Bellasitwasbehindthesubsequentincrediblegrowthoftheindustry."StartingwiththeintroductionofthesmallpremiumPETwatersthecategorystartedtoexplode"saysMr.Bellas."ThebottledwaterindustrybeforePETonthelistofallbeveragecategorieswasnumberseven.WiththeadventofPETwaterjumpedtothenumbertwospotbehindcarbonatedsoftdrinks." Bybrandingandmarketingwaterbottledwaterhasbeentransformedfromsomethingthatmanyofustookforgrantedintoaproductthatnowmakesbillionsforglobalmultinationalcompanies. 43
Withthespreadofinter-activeelectronicmediaamanaloneinhisownhomewillneverhavebeensowellplacedtofilltheinexplicablementalspacebetweencradleandcrematorium.SoIsuspectthatbookswillbepushedmoreandmoreintothosemomentsoftravelordifficultdefecation1peoplestilldon’tquiteknowwhattodowith. WhenpeopledoreadIthinkthey’llwanttofeeltheyarereadingliteratureor2somethingserious.3you’regoingtofindfewerbookspresentingthemselvesasno-nonsenseand4assumingliterarypretensionsandbeingpackagedasworksofart.Wecanexpectanextraordinaryvarietyofgenrebutwithanunderlying5ofsentimentandvision. Translatorscanonly6fromthisdesireforthepresumablysophisticated.Wecanlookforwardtolotsofdifficultnamesandfantasticstoriesofforeignpartsenthusiastically7bytheoverallworshipofthe"globalvillage"Muchofthiswillbeawfulandsomewonderful8don’texpectthepressortheorganizersofprizestoofferyoumuchhelpinmakingtheappropriatedistinctions.Theywillbechiefly9increatingcelebritythegreatestenemyofdiscriminationbutagoodpropforthe10consumer. Everyethnicgroupingovertheworldwillhavetobeseentohaveagreatwriter--aphenomenonthatwill11anewkindofprovincialismmorechronologicalthangeographic12onlythestrictlycontemporaryistalkedaboutand13.UniversitiesincludingCambridgewillinclude14theirliteraturesyllabusnovelswrittenonlylastyear.15occasionalexhumationfortheNobeltheachievementsoftenoronlyfiveyearsagowillbelargelyforgotten. Inshortyoucan’tgotoofarwrongwhenpredictingmoreofthesame.Butthereisa16sidetothis--theinevitablereactionagainstit.ThepracticalthingsIwouldliketoseehappen--publishersseekinglessto17celebritythroughextravagantadvertising18andmagazines19spacetoreflectivepieces--arerathermoreimprobablethantheSecondComing耶稣复临.Butdullnessneverquitedarkensthewholeplanet.Intheirownidiosyncraticfashionafewwriterswill20belookingfornewdepartures. 15
FewpeoplewoulddefendtheVictorianattitudetochildrenbutifyouwereaparentinthosedaysatleastyouknewwhereyoustood:childrenweretobeseenandnotheard.Freudandhiscompanydidawaywithallthatandparentshavebeenbewilderedeversince.Thechild’shappinessisall-importantthepsychologistssaybutwhatabouttheparents’happinessParentssuffercontinuallyfromfearandguiltwhiletheirchildrengailyrompaboutpullingtheplaceapart.Agood"old-fashioned"spankingisoutofthequestion:nomodernchild-rearingmanualwouldpermitsuchbarbarity.Thetroubleisyouarenotallowedeventoshout.WhoknowswhatdeeppsychologicalwoundsyoumightinflictThepoorchildmayneverrecoverfromthedreadfultraumaticexperience.Soitisthatparentsbendoverbackwardstoavoidgivingtheirchildrencomplexeswhichahundredyearsagohadn’tevenbeenheardof.Certainlyachildneedsloveandalotofit.Buttheexcessivepermissivenessofmodernparentsissurelydoingmoreharmthangood. Psychologistshavesucceededinunderminingparents’confidenceintheirownauthority.Andithasn’ttakenchildrenlongtogetwindofthefact.Inadditiontothegreatmodernclassicsonchild-caretherearecountlessarticlesinmagazinesandnewspapers.Withsomuchunsolicitedadviceflyingaboutmumanddadjustdon’tknowwhattodoanymore.Intheendtheydonothingatall.Sofromearlychildhoodthekidsareinchargeandparents’livesareregulatedaccordingtotheneedsoftheiroffspring.Whenthelittledearsdevelopintoteenagerstheytakecompletecontrol.Laxauthorityovertheyearsmakesadolescentrebellionagainstparentsallthemoreviolent.Iftheyoungpeoplearegoingtohaveapartyforinstanceparentsareaskedtoleavethehouse.Theirpresencemerelyspoilsthefun.Whatelsecanthepoorparentsdobutobey Childrenarehardycreaturesfarhardierthanthepsychologistswouldhaveusbelieveandmostofthemsurvivetheharmfulinfluenceofextremepermissivenesswhichisthenormalconditioninthemodernhousehold.Butagreatmanydonot.Thespreadofjuveniledelinquencyinourownageislargelyduetoparentallaxity.MotherbelievingthatlittleJohnnycanlookafterhimselfisnotathomewhenhereturnsfromschoolsolittleJohnnyroamsthestreets.Thedividing-linebetweenpermissivenessandsheernegligenceisveryfineindeed. Thepsychologistshavemuchtoanswerfor.Theyshouldkeeptheirmouthsshutandletparentsgetonwiththejob.Andifchildrenareknockedaboutalittlebitintheprocessitmaynotreallymattertoomuch.Atleastthiswillhelpthemtodevelopvigorousviewsoftheirownandgivethemsomethingpositivetoreactagainst.Perhapsthere’ssometruthintheideathatchildrenwhohavehadasurfeitofhappinessin.theirchildhoodappearlikestodgypuddingsandfail.tomakeasuccessoflife. Whatisimpliedinthefirstsentence
有5个进程PaPbPcPd和Pe它们依次进入就绪队列它们的优先级和需要的处理机时间如表2-14所示表2-14进程—处理机—优先级表进程处理机时间优先级Pa103Pb11Pc23Pd14Pe52忽略进程调度等所花费的时间请回答下列问题1分别写出采用先来先服务和非抢占式的优先数优先数大优先级低调度算法选中进程执行的次序2分别计算出上述两种算法使各进程在就绪队列中的等待时间及两种算法下的平均等待时间3某单处理机系统中采用多道程序设计现有10个进程存在则处于运行阻塞和就绪状态的进程数量最小和最大值分别可能是多少
Researchersinvestigatingbrainsizeandmentalabilitysaytheirworkoffersevidencethateducationprotectsthemindfromthebrain’sphysicaldeterioration. 46Itisknownthatthebrainshrinksasthebodyagesbuttheeffectsonmentalabilityaredifferentfrompersontoperson.Interestinglyinastudyofelderlymenandwomenthosewhohadmoreeducationactuallyhadmorebrainshrinkage. "Thatmayseemlikebadnews"saidstudyauthorDr.EdwardCoffeyaprofessorofpsychiatryandofneurologyatHenryFordHealthSysteminDetroit.47Howeverheexplainedthefindingsuggeststhateducationallowspeopletowithstandmorebraintissuelossbeforetheirmentalfunctioningbeginstobreakdown. ThestudypublishedintheJulyissueofNeurologyisthefirsttoprovidebiologicalevidencetosupportaconceptcalledthe"reserve"hypothesisaccordingtotheresearchers.Inrecentyearsinvestigatorshavedevelopedtheideathatpeoplewhoaremoreeducatedhavegreatercognitivereservestodrawuponasthebrainages;inessencetheyhavemorebraintissuetospare. 48Examiningbrainscansof320healthymenandwomenaged66to90researchersfoundthatforeachyearofeducationthesubjectshadtherewasgreatershrinkageoftheouterlayerofthebrainknownasthecortex.Yetontestsofcognitionandmemoryallparticipantsscoredintherangeindicatingnormal. "Everyonehassomedegreeofbrainshrinkage."Coffeysaid."Peopleloseonaverage2.5percentperdecadestartinginadulthood." Thereishowevera"remarkablerange"ofshrinkageamongpeoplewhoshownosignsofmentaldeclineCoffeynoted.Overallhealthhesaidaccountsforsomedifferencesinbrainsize.Alcoholordruguseaswellasmedicalconditionssuchasdiabetesandhighbloodpressurecontributetobraintissuelossthroughoutadulthood. IntheabsenceofsuchmedicalconditionsCoffeysaideducationlevelhelpsexplaintherangeofbrainshrinkageexhibitedamongthementally-fitelderly.Themore-educatedcanwithstandgreaterloss. 49Coffeyandcolleaguesgaugedshrinkageofthecortexbymeasuringthecerebrospinalfluid脑脊液surroundingthebrain.Thegreatertheamountoffluidthegreaterthecortical脑皮层的shrinkage. Controllingforthehealthfactorsthatcontributetobraininjurytheresearchersfoundthateducationwasrelatedtotheseverityofbrainshrinkage.Foreachyearofeducationfromfirstgradeonsubjectshadanaverageof1.77milliliters11morecerebrospinalfluidaroundthebrain.Justhoweducationmightaffectbraincellsisunknown.50Intheirreporttheresearchersspeculatedthatinpeoplewithmoreeducationcertainbrainstructuresdeeperthanthecortexmaystayintacttocompensateforcorticalshrinkage. 49Coffeyandcolleaguesgaugedshrinkageofthecortexbymeasuringthecerebrospinalfluid脑脊液surroundingthebrain.Thegreatertheamountoffluidthegreaterthecortical脑皮层的shrinkage.
Withthespreadofinter-activeelectronicmediaamanaloneinhisownhomewillneverhavebeensowellplacedtofilltheinexplicablementalspacebetweencradleandcrematorium.SoIsuspectthatbookswillbepushedmoreandmoreintothosemomentsoftravelordifficultdefecation1peoplestilldon’tquiteknowwhattodowith. WhenpeopledoreadIthinkthey’llwanttofeeltheyarereadingliteratureor2somethingserious.3you’regoingtofindfewerbookspresentingthemselvesasno-nonsenseand4assumingliterarypretensionsandbeingpackagedasworksofart.Wecanexpectanextraordinaryvarietyofgenrebutwithanunderlying5ofsentimentandvision. Translatorscanonly6fromthisdesireforthepresumablysophisticated.Wecanlookforwardtolotsofdifficultnamesandfantasticstoriesofforeignpartsenthusiastically7bytheoverallworshipofthe"globalvillage"Muchofthiswillbeawfulandsomewonderful8don’texpectthepressortheorganizersofprizestoofferyoumuchhelpinmakingtheappropriatedistinctions.Theywillbechiefly9increatingcelebritythegreatestenemyofdiscriminationbutagoodpropforthe10consumer. Everyethnicgroupingovertheworldwillhavetobeseentohaveagreatwriter--aphenomenonthatwill11anewkindofprovincialismmorechronologicalthangeographic12onlythestrictlycontemporaryistalkedaboutand13.UniversitiesincludingCambridgewillinclude14theirliteraturesyllabusnovelswrittenonlylastyear.15occasionalexhumationfortheNobeltheachievementsoftenoronlyfiveyearsagowillbelargelyforgotten. Inshortyoucan’tgotoofarwrongwhenpredictingmoreofthesame.Butthereisa16sidetothis--theinevitablereactionagainstit.ThepracticalthingsIwouldliketoseehappen--publishersseekinglessto17celebritythroughextravagantadvertising18andmagazines19spacetoreflectivepieces--arerathermoreimprobablethantheSecondComing耶稣复临.Butdullnessneverquitedarkensthewholeplanet.Intheirownidiosyncraticfashionafewwriterswill20belookingfornewdepartures. 19
ThemostthoroughlystudiedintellectualsinthehistoryoftheNewWorldaretheministersandpoliticalleadersofseventeenth-centuryNewEngland.AccordingtothestandardhistoryofAmericanphilosophynowhereelseincolonialAmericawas“somuchimportanceattachedtointellectualpursuits.”AccordingtomanybooksandarticlesNewEngland’sleadersestablishedthebasicthemesandpreoccupationsofanunfoldingdominantPuritantraditioninAmericanintellectuallife. TotakethisapproachtotheNewEnglandersnormallymeanstostartwiththePuritans’theologicalinnovationsandtheirdistinctiveideasaboutthechurch—importantsubjectsthatwemaynotneglect.ButinkeepingwithourexaminationofsouthernintellectuallifewemayconsidertheoriginalPuritansascarriersofEuropeancultureadjustingtoNewWorldcircumstances.TheNewEnglandcolonieswerethescenesofimportantepisodesinthepursuitofwidelyunderstoodidealsofcivilityandvirtuosity. TheearlysettlersofMassachusettsBayincludedmenofimpressiveeducationandinfluenceinEngland.BesidestheninetyorsolearnedministerswhocametoMassachusettschurchesinthedecadeafter1629therewerepoliticalleaderslikeJohnWinthropaneducatedgentlemanlawyerandofficialoftheCrownbeforehejourneyedtoBoston.ThesemenwroteandpublishedextensivelyreachingbothNewWorldandOldWorldaudiencesandgivingNewEnglandanatmosphereofintellectualearnestness. WeshouldnotforgethoweverthatmostNewEnglanderswerelesswelleducated.Whilefewcraftsmenorfarmersletalonedependentsandservantsleftliterarycompositionstobeanalyzeditisobviousthattheirviewswerelessfullyintellectualized.Theirthinkingoftenhadatraditionalsuperstitiousquality.AtailornamedJohnDanewhoemigratedinthelate1630sleftanaccountofhisreasonsforleavingEnglandthatisfilledwithsigns.Sexualconfusioneconomicfrustrationsandreligioushope—allcametogetherinadecisivemomentwhenheopenedtheBibletoldbasfatherthatthefirstlinehesawwouldsettlehisfateandreadthemagicalwords:"ComeoutfromamongthemtouchnouncleanthingandIwillbeyourGodandyoushallbemypeople."OnewonderswhatDanethoughtofthecarefulsermonsexplainingtheBiblethatheheardinPuritanchurches. MeanwhilemanysettlershadslighterreligiouscommitmentsthanDane’sasoneclergymanlearnedinconfrontingfolkalongthecoastwhomockedthattheyhadnotcometotheNewWorldfurreligion."Ourmainendwastocatchfish. ThestoryofJohnDaneshowsthatlesswell-educatedNewEnglanderswereoften
假设一个计算机系统具有如下性能特征处理一次中断平均耗用1毫秒一次进程调度平均需要2毫秒将CPU分配给选中的进程又需要平均1毫秒再假设其定时器芯片每秒产生100次中断请回答1操作系统将百分之几的CPU时间用于时钟中断处理2如果操作系统采用轮转法调度10个时钟中断为1个时间片那么操作系统将百分之几的CPU时间用于进程调度包括调度分配CPU和引起调度的时钟中断处理时间
[A]Convenientpackaging [B]Healthandwellness [C]Skepticalcustomers [D]Enormousmarkets [E]Soaringsales [F]Trendydrink Inthelast40yearsthebottledwaterindustryhasgonefromabusinessprospectthatfewtookseriouslytoaglobalindustryworthbillionsofpounds.Thecommodityitselfremainssimple.Thewaywethinkaboutithaschangedfundamentally.Waterisnaturalpureandsourcedatminimalcost.Itsrealvalueliesinitsmarketingandbranding."Ithinkbottledwateristhemostrevealingsubstanceforshowingushowtheglobalcapitalistmarketworkstoday"saysRichardWilkprofessorofanthropologyatIndianaUniversity."Inasensewe’rebuyingchoicewe’rebuyingfreedom.That’stheonlythingthatcanexplainwhyyouwouldpaymoneyforabottleofsomethingthatyoucanotherwisegetforfree." 41.______ Throughaconfectionofadvertisingandmarketingbottledwaterhasbecomeoneofthebiggestsuccessstoriesinthemodernfoodandbeverageindustry."Thedemandforbottlewaterhasgrownexponentiallyinthelastfewdecades"saysDr.PeterGleickauthorofBottledandSold."It’sdoubledit’sdoubledagainandit’sdoubledagain.Andthebottlewatercompaniesseeenormousmarketsnotjustintherichcountriesbutalsointhepoorercountries." Noactualvariety Somepeoplethinkthatbottledwateristhehighpointofglobalcapitalismparticularlythepeopleinthebottledwaterbusiness."Ithinkbottledwateractuallyrepresentsakindofcaricatureoftheglobaleconomy.Itprovidespeopleinthedevelopedworldwith20or30varietiesofsomethingforwhichthereisnoactualvariety"saysCharlesFishmanauthorofTheBigThirst. 42.______. Atthebeginningtherereallywasnovarietyandthebottledwaterphenomenonbeganwithonebrand.Perrier佩绿雅矿泉水品牌wasatriumphofadvertisingcreatingabrandthatwastodefineageneration.AttheheartofthecampaigntomakethebrandpopularwasRichardWheatleyoftheLeoBurnettadvertisingagencybetween1979and1994."Perrierpopularisedbottledwater"hesays."Itmadeitacceptablemorethanacceptableitmadeit...desirable."Butitwasnotaninstantsuccess.WhenPerrierUKwaslookingtoincreaseitssalesintheearly1970’sitfacedaskepticalpublic.Manyquestionedwhyanyonewouldbuywaterwhenyoucouldgetitfreefromthetap. 43.______. FacedwithobstaclesPerrierturnedtoadvertisingwithacampaignthatwastochangeourconsumerlandscapeforever.Thecampaignwasamarketingcoupandsaleswentthroughtherooffrom12millionbottlesin1980to152millionbytheendofthedecade.Perrierwasnolongerjustabottleofwater.Themarketingandadvertisingteamshadestablishedacrucialemotionallinkbetweentheproductandtheconsumers."Perrierbecameabadge"saysMichaelBellaschairmanoftheBeverageMarketingCorporation."WhenyouheldaPerrierbottleupitsaidsomethingaboutyourselfitsaidyouweresophisticatedyouunderstoodwhatwashappeningintheworld.Itwasaperfectbeveragefortheyoungandcomingbusinessexecutivesthetrend-setters." 44.______. Inanageofinstantgratificationstillwaterinportablebottlesprovidedwhatpeopleneededexactlywhentheyneededit."Peopleingeneralaremoreandmoretimepressed"saysMr.Fishman."Wedon’tcookourownmealsanymoreweeatpreparedfoodsofallkinds.Andthere’snothingmoreappealingthanabottleofcoldwateratamomentwhenyou’rereallythirsty.ButIthinkbottledwaterisoneofthoseproductsthatonmanyoccasionswhenpeoplebuyitwhatthey’rebuyingisn’tthewatersomuchasthebottle.Thatisthepackageandtheconvenienceatthatmoment." 45.______. WhenpeopleboughtthisconveniencewhattheywerereallybuyingwasPolyethyleneTerephthalateorPETthesinglemostimportantinnovationintheindustry’shistory.StrongshatterproofandahighlyvaluedformofpolyesterPETisaby-productoftheoilindustry.Itisnowutilisedinthepackagingofeverythingfrompharmaceuticalsandsoaptoreadymeals.InyearstocometheenvironmentalimpactofPETwouldhaunttheindustryandraisequestionsaboutitsverysurvivalbutinthe1990sthiswasarevolution.AccordingtoMr.Bellasitwasbehindthesubsequentincrediblegrowthoftheindustry."StartingwiththeintroductionofthesmallpremiumPETwatersthecategorystartedtoexplode"saysMr.Bellas."ThebottledwaterindustrybeforePETonthelistofallbeveragecategorieswasnumberseven.WiththeadventofPETwaterjumpedtothenumbertwospotbehindcarbonatedsoftdrinks." Bybrandingandmarketingwaterbottledwaterhasbeentransformedfromsomethingthatmanyofustookforgrantedintoaproductthatnowmakesbillionsforglobalmultinationalcompanies. 41
Gallowayamostlymiddle-classcommunitynorthwestofAtlanticCityispartofawaveofdistrictsacrossthenationtryingtoremakehomeworkamidconcernsthathigh-stakestestingandcompetitionforcollegehavefueledanightlygrindthatisstressingoutchildrenanddeprivingthemofplayandrestyetdoinglittletoraiseachievementparticularlyinelementarygrades. Sucheffortshavedrawncriticismfromsometeachersandsomeparentswhocounterthatstudentsmuststudymorenotlessiftheyaretosucceed.Evensotheanti-homeworkmovementhasbeenreignitedinrecentmonthsbythedocumentaryRacetoNowhereaboutburned-outstudentscaughtinapressure-cookereducationalsystem."Thereissimplynoproofthatmosthomeworkasweknowitimprovesschoolperformance"saidVickiAbelesthefilmmakerandamotherofthreefromCalifornia."Andbyexpectingkidstoworka’secondshift’inwhatshouldbetheirdowntimethepresenceofschoolworkathomeisnegativelyaffectingthehealthofouryoungpeopleandthequalityoffamilytime." SoteachersatMangoElementarySchoolinFontanaCalif.arereplacinghomeworkwith"goalwork"thatisspecifictoindividualstudent’sneedsandthatcanbecompletedinclassorathomeathisorherownpace.TheBrooklynSchoolofInquiryagiftedandtalentedprogramhasmadehomeworkoptional."Ithinkpeopleconfusehomeworkwithrigor"saidDonnaTaylortheBrooklynSchool’sprincipalwhoviewshomeworkforchildrenunder11asprimarilybenefitingparentsbyhelpingthemfeelconnectedtotheclassroom. Researchhaslongsuggestedthathomeworkinsmalldosescanreinforcebasicskillsandhelpyoungchildrendevelopstudyhabitsbutthattherearediminishingreturns.Stilleffortstorollbackhomeworkhavebeenopposedbythosewhocounterthatthereisnotenoughtimeintheschooldaytocoverrequiredtopicsandthathomeworkreinforcesclassroomlearning.InCoronadoCalif.theschoolboardrejectedaproposalbythesuperintendenttoeliminatehomeworkonweekendsandholidaysaftersomeparentssaidthatwaswhentheyhadtimetohelptheirchildrenandothersworrieditwouldresultinmorehomeworkonweeknights. Homeworkwarshavedividedcommunitiesforoveracentury.Inthe1950stheSputniklaunchingusheredinheavierworkloadsforAmericanstudentsintheracetokeepupwiththeSovietUnion.The1983report"ANationatRisk"andmorerecentlythetestingpressuresoftheNoChildLeftBehindlawalsoresultedinmorehomeworkforchildrenatyoungerages.Afewpublicandprivateschoolshaverenouncedhomeworkinrecentyearsbutmosthavesoughtamiddleground.InGallowaythepolicywouldstipulatethathomeworkcoveronlytopicsalreadyaddressedinclass.Dr.GiaquintoGalloway’ssuperintendentsaidthegoaloftheproposedpolicywastomakehomework"meaningfulandmanageable"notingthatteacherswouldhavetocoordinateassignmentssothatastudent’stotalhomeworkwouldnotexceedthetimelimit. Increasedhomeworkhadresultedfrom
某系统中进程有如图2-16所示的状态变化 请回答下列问题 把图中发生①~④的状态变化原因填入表2-12中
设系统中有下述解决死锁的办法1银行家算法2检测死锁终止处于死锁状态的进程释放该进程所占有的资源3资源预分配请问哪种办法允许最大的并发性即哪种办法允许更多的进程无等待地向前推进请按并发性从大到小对上述三种办法进行排序
ThemostthoroughlystudiedintellectualsinthehistoryoftheNewWorldaretheministersandpoliticalleadersofseventeenth-centuryNewEngland.AccordingtothestandardhistoryofAmericanphilosophynowhereelseincolonialAmericawas“somuchimportanceattachedtointellectualpursuits.”AccordingtomanybooksandarticlesNewEngland’sleadersestablishedthebasicthemesandpreoccupationsofanunfoldingdominantPuritantraditioninAmericanintellectuallife. TotakethisapproachtotheNewEnglandersnormallymeanstostartwiththePuritans’theologicalinnovationsandtheirdistinctiveideasaboutthechurch—importantsubjectsthatwemaynotneglect.ButinkeepingwithourexaminationofsouthernintellectuallifewemayconsidertheoriginalPuritansascarriersofEuropeancultureadjustingtoNewWorldcircumstances.TheNewEnglandcolonieswerethescenesofimportantepisodesinthepursuitofwidelyunderstoodidealsofcivilityandvirtuosity. TheearlysettlersofMassachusettsBayincludedmenofimpressiveeducationandinfluenceinEngland.BesidestheninetyorsolearnedministerswhocametoMassachusettschurchesinthedecadeafter1629therewerepoliticalleaderslikeJohnWinthropaneducatedgentlemanlawyerandofficialoftheCrownbeforehejourneyedtoBoston.ThesemenwroteandpublishedextensivelyreachingbothNewWorldandOldWorldaudiencesandgivingNewEnglandanatmosphereofintellectualearnestness. WeshouldnotforgethoweverthatmostNewEnglanderswerelesswelleducated.Whilefewcraftsmenorfarmersletalonedependentsandservantsleftliterarycompositionstobeanalyzeditisobviousthattheirviewswerelessfullyintellectualized.Theirthinkingoftenhadatraditionalsuperstitiousquality.AtailornamedJohnDanewhoemigratedinthelate1630sleftanaccountofhisreasonsforleavingEnglandthatisfilledwithsigns.Sexualconfusioneconomicfrustrationsandreligioushope—allcametogetherinadecisivemomentwhenheopenedtheBibletoldbasfatherthatthefirstlinehesawwouldsettlehisfateandreadthemagicalwords:"ComeoutfromamongthemtouchnouncleanthingandIwillbeyourGodandyoushallbemypeople."OnewonderswhatDanethoughtofthecarefulsermonsexplainingtheBiblethatheheardinPuritanchurches. MeanwhilemanysettlershadslighterreligiouscommitmentsthanDane’sasoneclergymanlearnedinconfrontingfolkalongthecoastwhomockedthattheyhadnotcometotheNewWorldfurreligion."Ourmainendwastocatchfish. Itissuggestedinparagraph2thatNewEnglanders
Researchersinvestigatingbrainsizeandmentalabilitysaytheirworkoffersevidencethateducationprotectsthemindfromthebrain’sphysicaldeterioration. 46Itisknownthatthebrainshrinksasthebodyagesbuttheeffectsonmentalabilityaredifferentfrompersontoperson.Interestinglyinastudyofelderlymenandwomenthosewhohadmoreeducationactuallyhadmorebrainshrinkage. "Thatmayseemlikebadnews"saidstudyauthorDr.EdwardCoffeyaprofessorofpsychiatryandofneurologyatHenryFordHealthSysteminDetroit.47Howeverheexplainedthefindingsuggeststhateducationallowspeopletowithstandmorebraintissuelossbeforetheirmentalfunctioningbeginstobreakdown. ThestudypublishedintheJulyissueofNeurologyisthefirsttoprovidebiologicalevidencetosupportaconceptcalledthe"reserve"hypothesisaccordingtotheresearchers.Inrecentyearsinvestigatorshavedevelopedtheideathatpeoplewhoaremoreeducatedhavegreatercognitivereservestodrawuponasthebrainages;inessencetheyhavemorebraintissuetospare. 48Examiningbrainscansof320healthymenandwomenaged66to90researchersfoundthatforeachyearofeducationthesubjectshadtherewasgreatershrinkageoftheouterlayerofthebrainknownasthecortex.Yetontestsofcognitionandmemoryallparticipantsscoredintherangeindicatingnormal. "Everyonehassomedegreeofbrainshrinkage."Coffeysaid."Peopleloseonaverage2.5percentperdecadestartinginadulthood." Thereishowevera"remarkablerange"ofshrinkageamongpeoplewhoshownosignsofmentaldeclineCoffeynoted.Overallhealthhesaidaccountsforsomedifferencesinbrainsize.Alcoholordruguseaswellasmedicalconditionssuchasdiabetesandhighbloodpressurecontributetobraintissuelossthroughoutadulthood. IntheabsenceofsuchmedicalconditionsCoffeysaideducationlevelhelpsexplaintherangeofbrainshrinkageexhibitedamongthementally-fitelderly.Themore-educatedcanwithstandgreaterloss. 49Coffeyandcolleaguesgaugedshrinkageofthecortexbymeasuringthecerebrospinalfluid脑脊液surroundingthebrain.Thegreatertheamountoffluidthegreaterthecortical脑皮层的shrinkage. Controllingforthehealthfactorsthatcontributetobraininjurytheresearchersfoundthateducationwasrelatedtotheseverityofbrainshrinkage.Foreachyearofeducationfromfirstgradeonsubjectshadanaverageof1.77milliliters11morecerebrospinalfluidaroundthebrain.Justhoweducationmightaffectbraincellsisunknown.50Intheirreporttheresearchersspeculatedthatinpeoplewithmoreeducationcertainbrainstructuresdeeperthanthecortexmaystayintacttocompensateforcorticalshrinkage. 47Howeverheexplainedthefindingsuggeststhateducationallowspeopletowithstandmorebraintissuelossbeforetheirmentalfunctioningbeginstobreakdown.
设某计算机系统有一块CPU一台输入设备一台打印机现有两个进程同时进入就绪状态且进程A先得到CPU运行进程B后运行进程A的运行轨迹为计算50毫秒打印信息100毫秒再计算50毫秒打印信息100毫秒结束进程B的运行轨迹为计算50毫秒输入数据80毫秒再计算100毫秒结束试说明进程A运行时有无等待现象若有在什么时候发生等待现象
某一个操作系统具有分时兼批处理的功能设计一个合理的队列调度策略使得分时作业响应快批作业也能及时得到处理
系统有同类资源10个进程P1P2和P3需要该类资源的最大数量分别为867它们使用资源的次序和数量如表2-11所示试给出采用银行家算法分配资源时进行第5次分配后各进程的状态及各进程占用资源的情况
Withthespreadofinter-activeelectronicmediaamanaloneinhisownhomewillneverhavebeensowellplacedtofilltheinexplicablementalspacebetweencradleandcrematorium.SoIsuspectthatbookswillbepushedmoreandmoreintothosemomentsoftravelordifficultdefecation1peoplestilldon’tquiteknowwhattodowith. WhenpeopledoreadIthinkthey’llwanttofeeltheyarereadingliteratureor2somethingserious.3you’regoingtofindfewerbookspresentingthemselvesasno-nonsenseand4assumingliterarypretensionsandbeingpackagedasworksofart.Wecanexpectanextraordinaryvarietyofgenrebutwithanunderlying5ofsentimentandvision. Translatorscanonly6fromthisdesireforthepresumablysophisticated.Wecanlookforwardtolotsofdifficultnamesandfantasticstoriesofforeignpartsenthusiastically7bytheoverallworshipofthe"globalvillage"Muchofthiswillbeawfulandsomewonderful8don’texpectthepressortheorganizersofprizestoofferyoumuchhelpinmakingtheappropriatedistinctions.Theywillbechiefly9increatingcelebritythegreatestenemyofdiscriminationbutagoodpropforthe10consumer. Everyethnicgroupingovertheworldwillhavetobeseentohaveagreatwriter--aphenomenonthatwill11anewkindofprovincialismmorechronologicalthangeographic12onlythestrictlycontemporaryistalkedaboutand13.UniversitiesincludingCambridgewillinclude14theirliteraturesyllabusnovelswrittenonlylastyear.15occasionalexhumationfortheNobeltheachievementsoftenoronlyfiveyearsagowillbelargelyforgotten. Inshortyoucan’tgotoofarwrongwhenpredictingmoreofthesame.Butthereisa16sidetothis--theinevitablereactionagainstit.ThepracticalthingsIwouldliketoseehappen--publishersseekinglessto17celebritythroughextravagantadvertising18andmagazines19spacetoreflectivepieces--arerathermoreimprobablethantheSecondComing耶稣复临.Butdullnessneverquitedarkensthewholeplanet.Intheirownidiosyncraticfashionafewwriterswill20belookingfornewdepartures. 17
Gallowayamostlymiddle-classcommunitynorthwestofAtlanticCityispartofawaveofdistrictsacrossthenationtryingtoremakehomeworkamidconcernsthathigh-stakestestingandcompetitionforcollegehavefueledanightlygrindthatisstressingoutchildrenanddeprivingthemofplayandrestyetdoinglittletoraiseachievementparticularlyinelementarygrades. Sucheffortshavedrawncriticismfromsometeachersandsomeparentswhocounterthatstudentsmuststudymorenotlessiftheyaretosucceed.Evensotheanti-homeworkmovementhasbeenreignitedinrecentmonthsbythedocumentaryRacetoNowhereaboutburned-outstudentscaughtinapressure-cookereducationalsystem."Thereissimplynoproofthatmosthomeworkasweknowitimprovesschoolperformance"saidVickiAbelesthefilmmakerandamotherofthreefromCalifornia."Andbyexpectingkidstoworka’secondshift’inwhatshouldbetheirdowntimethepresenceofschoolworkathomeisnegativelyaffectingthehealthofouryoungpeopleandthequalityoffamilytime." SoteachersatMangoElementarySchoolinFontanaCalif.arereplacinghomeworkwith"goalwork"thatisspecifictoindividualstudent’sneedsandthatcanbecompletedinclassorathomeathisorherownpace.TheBrooklynSchoolofInquiryagiftedandtalentedprogramhasmadehomeworkoptional."Ithinkpeopleconfusehomeworkwithrigor"saidDonnaTaylortheBrooklynSchool’sprincipalwhoviewshomeworkforchildrenunder11asprimarilybenefitingparentsbyhelpingthemfeelconnectedtotheclassroom. Researchhaslongsuggestedthathomeworkinsmalldosescanreinforcebasicskillsandhelpyoungchildrendevelopstudyhabitsbutthattherearediminishingreturns.Stilleffortstorollbackhomeworkhavebeenopposedbythosewhocounterthatthereisnotenoughtimeintheschooldaytocoverrequiredtopicsandthathomeworkreinforcesclassroomlearning.InCoronadoCalif.theschoolboardrejectedaproposalbythesuperintendenttoeliminatehomeworkonweekendsandholidaysaftersomeparentssaidthatwaswhentheyhadtimetohelptheirchildrenandothersworrieditwouldresultinmorehomeworkonweeknights. Homeworkwarshavedividedcommunitiesforoveracentury.Inthe1950stheSputniklaunchingusheredinheavierworkloadsforAmericanstudentsintheracetokeepupwiththeSovietUnion.The1983report"ANationatRisk"andmorerecentlythetestingpressuresoftheNoChildLeftBehindlawalsoresultedinmorehomeworkforchildrenatyoungerages.Afewpublicandprivateschoolshaverenouncedhomeworkinrecentyearsbutmosthavesoughtamiddleground.InGallowaythepolicywouldstipulatethathomeworkcoveronlytopicsalreadyaddressedinclass.Dr.GiaquintoGalloway’ssuperintendentsaidthegoaloftheproposedpolicywastomakehomework"meaningfulandmanageable"notingthatteacherswouldhavetocoordinateassignmentssothatastudent’stotalhomeworkwouldnotexceedthetimelimit. Criticismsofhomeworkaremainlybasedonthepremisethat
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