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某物理兴趣小组的同学，用煤炉给10dm3的水加热，同时他们绘制了如图所示的加热过程中水温随时间变化的图线．若在6min内完全燃烧了2kg的煤，水的比热容为4.2×103J/（kg•℃），煤的热值约为...
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某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图18所示的加热过程中水温随时间变化的图
某物理兴趣小组的同学用煤炉给10kg15℃的水加热若在6min内完全燃烧了2kg的煤水温升至75℃[
某物理兴趣小组的同学用煤炉给l0kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线若
某物理兴趣小组的同学用煤炉给8kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线若在
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线.
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线.
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图l4所示的加热过程中水温随时间变化的图
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线.
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线若
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线若
分某物理兴趣小组的同学用煤炉给l0kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线
某物理兴趣小组的同学用煤炉给10kg的水加热同时绘制了如图所示的加热过程中水温随时间变化的图线若在6
某物理兴趣小组的同学用煤炉给l0kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线.
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图13-Z-7所示的加热过程中水温随时间
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线.
分某物理兴趣小组的同学用煤炉给l0kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线
某物理兴趣小组的同学用煤炉给lOkg的水加热同时他们绘制了如图l4所示的加热过程中水温随时间变化的图
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线若
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图l4所示的加热过程中水温随时间变化的图
某物理兴趣小组的同学用煤炉给10kg的水加热同时他们绘制了如图所示的加热过程中水温随时间变化的图线.
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HowtoGettheBestHotelDeal Takingtheentirefamilyonvacationcanaddupquickly﹣﹣﹣﹣flightsrentalcargasmealssnacksandofcoursehotels.HoweverbydoingsomeresearchandusingthreelittlewordsyoucouldendupsavingalotofmoneyonaccommodationsFirstsearchhotelbookingsiteslikeTripAdvisororExpediaandcheckoutthehotelratesinyourlocationforthedatesyouwouldliketobook.Takedownallthepricesyoufindonlineforthathotel.Butevenifyoufindastealofadealoraspecialdiscountdon'tpressthebookbuttononthewebsitejustyet. Afterresearchingpricesonlineexpertssaythebestwaytogetthelowesthotelrateistocallthehoteldirectly﹣﹣﹣﹣notanyofthecustomerserviceor1﹣800numbersthatcouldbelistedasacontactnumberespeciallyforachainhotel.Thenyou'regoingtodropsomemagicwords.Awhileyoumightbetemptedtoaskforthebestdealorthelowestrateyoursecretweaponhereistousethephrasecheapestnonrefundablerate.AccordingtoexpertsatTravel+Leisurethatphrasetriggershotelstafftosearchfortheroomthatwillcostyoutheleastforyourvacation. Ifyoudoenduptryingtonegotiateabetterpricementionthenumbersyoufoundonlineandthenreducethosepricesby20percent.Apparentlyhotelspayaheftyfeetobelistedonhotelbookingsitesandthat20percentcouldactuallymeanmoremoneythantheywouldgetifyoubookedthroughoneofthem. Justdon'twaituntilthelastminutetoscoreadealbecausethatcanleadtopayingmorenotless.FredLalondefounderofthetravelserviceHoppertoldTravel+Leisurethatthebestdealsonhotelsareusuallyavailabletwotothreemonthsaheadofthevacationdatepotentiallysavingyoumorethan﹩270foraneight﹣daystay. 1WhatdoestheunderlinedpartthreelittlewordsinParagraph1referto? A.Aspecialdiscount B.Thebestdeal C.Thelowestrate D.Cheapestnonrefundablerate. 2Accordingtothepassagethepreferredwaytogetthebesthoteldealisto. A.callthetargethotelstobargainwiththestaff. B.collectandcomparethepricesfoundonline C.bookhotelsjustbeforeyourdeparturetime D.turntohotelbookingsitesforadiscount
已知函数fx＝1nx+x． 1求函数在点1f1处的切线方程 2若ax≥fx对任意的x∈[+∞恒成立求实数a的取值范围．
已知x+12x+n的展开式中没有x2项n∈N*则n的值可以是
在空间四边形OABC中若⊥⊥∠BOC＝且||＝||＝||＝1若EF分别是ABBC的中点H是EF上一点且EH＝EF记＝x+y+z则xyz＝
Onedayin1995alargeheavymiddle﹣agedmanrobbedtwoPittsburghbanksinbroaddaylight.Hedidn'twearamaskandhesmiledatsurveillancecamerasbeforewalkingoutofeachbank.LaterthatnightpolicearrestedasurprisedMcArthurWheeler.WhentheyshowedhimthesurveillancetapesWheelerstaredindisbelief.ButIworethejuicehemumbled.ApparentlyWheelerthoughtthatrubbinglemonjuiceonhisskinwouldmakehiminvisibletovideotapecameras.Afteralllemonjuiceisusedasinvisibleinksoaslongashedidn'tcomenearaheatsourceheshouldhavebeencompletelyinvisible. ThecasecaughttheeyeofthepsychologistDavidDunningatCornellUniversitywhoenlistedhisgraduatestudentJustinKrugertoseewhatwasgoingon.Theyreasonedthatwhilealmosteveryoneholdsfavourableviewsoftheirabilitiesinvarioussocialandintellectualfieldssomepeoplemistakenlyassesstheirabilitiesasbeingmuchhigherthantheyactuallyare.ThisillusionofconfidenceisnowcalledtheDunning﹣Krugereffectanddescribesthecognitivebiastoinflateself﹣assessment. ToinvestigatethisphenomenoninthelabDunningandKrugerdesignedsomecleverexperiments.Inonestudytheyaskedundergraduatestudentsaseriesofquestionsaboutgrammarlogicandjokesandthenaskedeachstudenttoestimatehisorherscoreoverallaswellastheirrelativerankingscomparedtotheotherstudents.Interestinglystudentswhoscoredthelowestinthesecognitivetasksalwaysoverestimatedhowwelltheydid﹣byalot.Studentswhoscoredinthebottomestimatedthattheyhadperformedbetterthantwo﹣thirdsoftheotherstudents! Sureit'stypicalforpeopletooverestimatetheirabilities.Theproblemisthatwhenpeopleareincompetentnotonlydotheyreachwrongconclusionsandmakeunfortunatechoicesbutalsotheyarerobbedoftheabilitytorealizetheirmistakes.Inasemester﹣longstudyofcollegestudentsgoodstudentscouldbetterpredicttheirperformanceonfutureexamsgivenfeedbackabouttheirscoresandrankings.Howeverthepoorestperformersshowednorecognitiondespiteclearandrepeatedfeedbackthattheyweredoingbadly.Insteadofbeingconfusedorthoughtfulabouttheirincorrectwaysincompetentpeopleinsistthattheirwaysarecorrect.AsCharlesDarwinwroteinTheDescentofMan1871Ignorancemorefrequentlybegetsconfidencethandoesknowledge. Interestinglyreallysmartpeoplealsofailtoaccuratelyself﹣assesstheirabilities.AsmuchasD﹣andF﹣gradestudentsoverestimatetheirabilitiesA﹣gradestudentsunderestimatetheirs.Thedifferenceisthatcompetentpeoplecananddoadjusttheirself﹣assessmentgivenappropriatefeedbackwhileincompetentindividualscannot. 1WhichofthefollowingstatementsabouttheDunning﹣KrugereffectisTRUE? A.Theeffectistrueforeveryoneindailylife. B.Itsuggeststhatmostpeoplelackcognitiveabilities. C.Somepeopleareoverconfidentabouttheirabilities. D.Theconclusionisdrawnbasedonaseriesofbankrobberies. 2Whatdothecollegestudents'behaviorsmentionedintheexperimentsprove? A.Feedbackplaysasignificantroleinestimatingone'sability. B.Incompetentpeoplehavearigidattitudetowardstheirchoice. C.Goodstudentscanpredicttheirfutureperformanceaccurately. D.Peoplecan'trelyontheirpreviousbehaviortomakeadjustments. 3TheunderlinedwordbegetsinParagraph4canbereplacedby. A.givesriseto B.takesadvantageof C.makesupfor D.breaksawayfrom 4Whatcanweinferfromthepassage? A.Realknowledgeisknowingtheextentofone'signorance. B.Itisdifficultforpeopletoevaluatetheirrealcompetence. C.Illusionofconfidenceisthemajorsourceofpeople'sfailure. D.Thosewithgreatabilitiesoftenhavealowopinionofthemselves.
请阅读下面文字和图表并按要求用英语写一篇150词左右的文章Chinesetourismindustryisrelativelyyoungbutveryattractive.With288billiondollarsspentworldwidein2018Chinesetourists'spendingrepresentsaquarterofglobaltourismspending.NowadaystravelingiseasierthansomeyearsagoandvisitingaforeigncountryisascommonasmovinginChina.ForthisreasonwhenChinesetouristsplantheirholidaytheyoftenhavethedilemmawhetheritisbettertomoveabroadortostayinChina.Chinahasthelargestoutbound出境的tourismmarket.Indeedmorethan71millionChinesetouriststraveledabroadin201815percentmorethanthepreviousyear.Thisphenomenonisduetodifferentfactorsthefirstonebeingrisingincomes.Themiddle﹣classhasthemeanstotraveloutsideChina.Thesecondoneisanincreaseinonlineinformationwithacontentofquality.WordofmouthandrecommendationsfromfriendsarethemostfavoredsourceofinformationofChinesetourists.Thethirdfactorwouldbefriendliervisapoliciesfromforeigngovernments.[写作内容]1.用约30个单词概括上述信息的主要内容2.结合上述信息用约120个单词发表你的观点内容包括你对'境外旅游热'持什么观点?说明你的理由至少两点若你所在城市正大力推广本地旅游业你认为应该采取哪些促进措施?[写作要求]1.写作过程中不能直接引用原文语句2.作文中不能出现真实姓名和学校名称3.不必写标题.[评分标准]内容完整语言规范语篇连贯词数适当.
Thereisa1930s﹣oldrestaurantinmyhometownthathasdonelittletoupdateitselfoverthepast80years.Thisispartofitscharmasisthewoodenphonebooththatsitsneglectedintheageofthecellphone. Ahthephonebooth.Weneeditnowmorethanever. Formeitsymbolizesthatphonecallswereonceprivateaffairseveniftheinformationbeingsharedwasnotsensitiveinanyway.Itwassimplyassumedthataphoneconversationwasmeantfortwopeopleandtwopeopleonly.Inpublicplacesthismeantturningtothephonebooth﹣aprivatechamberwhereonecouldconverseinpeacewithoutbeingoverheard. Evenathomephonecallsusedtoberegardedasprivate.Growingupinthe1960swehadonephoneinthehouse﹣fixedtothekitchenwall. AsakidIdidn'tgetormakemanycalls.Idohoweverrememberansweringthephoneaskingfortheidentityofthecallerandthenhandingthephonetomymom.She'dtakeitsayHelloMrs.FlaubertandthenonemomentpleaseassheplacedherhandoverthereceiverturnedtomeanddirectedThisisforme.Whydon'tyougooutsideandplay? Flash﹣forwardtowhatcellphoneshavedonetothisidyll.Withinthespaceofveryfewyearsprivateconversationshavebecomepublicdeclarationandbeingoverheardseemstobethepoint.Alargepartoftheproblemofcourseisthatwenowcarryourphoneswithusandthereflex反射toanswerthedeviceassoonasitringsisaresponsePavlovwouldhaveappreciated. Buttheinformationisrevealed!NotlongagoIwassittinginBoston'sSouthStationwaitingformytrain.AfterpurchasingasandwichIsatdownatatablenearamanwhowasonhiscellphone. LetmeparaphrasewhatthemanhadtosayYesthat'sright.Theredandyellowroses.ThatwillbeaVisa.Thenheproceededtorecitehiscardnumberandexpirationdatebeforesigningoff. Istaredunbelievablyatthefellow.HeglancedatmeandaskedWhat? MyresponsewasimmediateIrecitedhiscardnumberbacktohimalongwiththeexpirationdate. Thereisnomoreprivacynolongerasenseofpersonalbordersorlimitsandthecellphonehasbecomealoudspeaker. ToreturntophoneboothsWhydidtheydisappear?AndshouldyouthinkaphoneboothhasnovaluetodayIsawoneoneBaygoingfor＄4750. 1Whydoprivateconversationsturnintopublicdeclarationaccordingtothepassage? A.Phoneboothshavediedoutinmodernlife. B.Peoplelackasenseofpersonalbordersorlimits. C.Thecontentofphonecallsisnotthatsensitive. D.Itisconvenientforpeopletoreachforcellphones. 2BydescribingwhathappenedinBoston'sSouthStationtheauthorindicatesthat. A.it'sridiculoustoanswercellphonesinpublicplaces B.it'simpolitetooverhearothersansweringcellphones C.it'snecessarytokeepasafedistancefromotherswhenansweringphones D.it'sinappropriatetotouchonpersonalinformationincellphoneconversations 3Whatcanweconcludefromthepassage? A.Pavlovisinfavorofansweringcellphonesinstantly. B.Somethingseeminglyold﹣fashionedholdsitscharmtoday. C.PhoneboothsareverypopularwithconsumersontheInternet. D.Peopleusedtolackasenseoftrustandsecurityinthe1960s.
已知fx＝f-1＝若fa＝1则实数a的值为．
已知函数fx＝3x2则fx在x＝3处的导数为
已知a＞b＞0则下列不等式正确的是
如图FA⊥平面ABC∠ABC＝90°EC∥FAFA＝3EC＝1AB＝2AC＝4BD⊥AC交AC于点D． Ⅰ证明FD⊥BE Ⅱ求直线BC与平面BEF所成角的正弦值．
已知向量＝x11＝410||＝则x＝•＝．
如图F是椭圆C＝1a＞b＞0的右焦点直线ABx-2y+2＝0与椭圆C相切于点A Ⅰ若a＝求b Ⅱ若||＝||＝0求椭圆C的方程．
Whileabruteforceapproachtolearningmaygetthejobdoneit'snotnecessarilythebeststudyplan.Wedugthroughscientificresearchtoidentifyfivestudymethodsthatarerecommendedbycognitivescientists.Thesestudytipsmayimprovetheefficiencyofhowyoustudyhelpingyoutolearnmoreinlesstimeandkeepitlonger. Don'tWaitUntiltheLastMinute Parentsandteachersoftenwarnthatcrammingforexamsisn'tthebestwaytogetgoodgrades.There'ssciencetobackthisup.Researchersfoundthatfinaltestresultsimprovedwhenstudyingwasspacedoutovertime.Thisspacingeffecthasbeenrepeatedlystudiedandoneresearchexperimentfounda36%improvementingradesbecauseofspacingoutstudysessions.Byspacingoutstudysessionsthere'saneural神经的processoflearningforgettingalittlebitandre﹣learning.Thesecyclesarewhatbuildstrongermemory. UsePracticeTests Usingpracticetestswhilepreparingforexamscanhelpyouimproveyourperformance.Thislearningstrategyisn'tjustaboutbecomingfamiliarwithatestingformatit'saboutreinforcingthebrain'smemory. Rememberthatre﹣readingmaterialcanrefreshyourawarenessbutitwon'thelpyoubuildthememoryrecallskillsthatcanhelpyouknowthecorrectanswerduringyourexam.Abetterwaytostudyistouseflashcardsorsamplequizzesfromyourtextbook. DoOneThingataTime Researchshowsthatmultitaskingisn'tgoodforyourmemorysowhenyou'restudyingthat'stheonlythingyoushouldbedoing.ConsideryourbrainpowersimilartoyourInternetbandwidth.Multipledownloadsatthetimewillslowthingsdown.Similarlymultitaskingcausesanincreasedcognitiveloadforyourbrainreducingyourabilitytopayattentiontowhatyou'relearning. Infactresearchersfoundthatevenminimalmultitaskinghasaneffect.Somethingassimpleaswalkingaroundatrackwhilelearningvocabularywordscauseda17%reductionintestscores. AddVariety Whileit'sagoodideatoonlystudyforonesubjectatatimescientistsfoundthatalternatingbetweensubtopicscoulddramaticallyimprovememory. Thisprocessknownasinterleavingmeansthatyou'llcyclethroughaboutthreesubtopicslearningalittlebitmoreabouteachduringeachcycle.Onceyou'vefullystudiedthissetandhaveanunderstandingofthematerialyoucanmoveontothenextsetandrepeatthepattern. TeachaFriend It'slongbeensaidthatthebestwaytolearnsomethingistoteachittosomeoneelse.KnownastheprotégéeffectthislearningtheorydatesbacktoancientRome. Thereasonthestudytechniquehaslastedsolongisthatit'seffective.Researchersfoundthatevenexplainingclassmaterialtoyourselfcouldresultinthreetimesbettertestscoresthanthoseofotherstudentsputtingyouwellahead. Fivelearningstrategiestobe1inyourstudy Passageoutline Supportingdetails Don'twaituntilthelastminute ●Thereisscientificevidenceto2thefactthatcrammingforexamsdoesnotnecessarilybringaboutgoodgrades. ●Insteadofspacingoutstudysessionsstudentstendtopreparefortheirtestsina3. Usepracticetests ●Practicetestsarenotmerelyintendedtomakestudents4withtestingformatsbutreinforcedthebrain'smemory. ●Re﹣readingmaterialcanmakeyou5ofwhatyouhavelearntwhileflashcardsorsamplequizzescanbuildmemoryrecallskills. 6multitasking Multipletaskscanreducetheabilitytofocusonwhatisbeinglearned. Involvesubtopicsinyourstudy ●Studyingforonesubjectatatimeisrecommendedbutalternatingbetweensubtopicsleadstodramatic7inmemory. ●Interleavingisalearningprocesswherestudentslearnaboutthreesubtopicsineach8. Teachafriend ●Protégéeffectisalearningtheoryinwhichstudentscan9fromteachingsomeoneelse. ●Explainingclassmaterialtooneselfmay10.
已知椭圆C+＝1a＞0b＞0的长轴长为4离心率为． Ⅰ求椭圆C的方程 Ⅱ当a＞b时设Mm0m∈R过M作直线l交椭圆C于PQ两点记椭圆C的左顶点为A直线APAQ的斜率分别为k1k2且k1k2＝-求实数m的值．
从甲乙丙丁四人中选取两人参加某项活动则甲乙两人有且仅有一人入选的概率为
已知椭圆C1m2x2+y2＝10＜m＜1与双曲线C2n2x2-y2＝1n＞0有共同的焦点e1e2分别为C1C2的离心率则e1•e2的取值范围是
已知P为双曲线-＝1a＞0b＞0右支上一点A为其左顶点F40为其右焦点满足|AF|＝|PF|∠PFA＝则点F到直线PA的距离为
InAHistoryofReadingtheCanadiannovelistAlbertoMangueldescribesaremarkabletransformationofhumanconsciousnesswhichtookplacearoundthe10thcenturyA.D.thearrivalofsilentreading.Humanbeingshavebeenreadingforthousandsofyearsbutinancienttimesthenormalthingwastoreadaloud.WiththearrivalofsilentreadingManguelwrites…thereaderwasatlastabletoestablishanunrestrictedrelationshipwiththebookandthewords.Thewordsnolongerneededtooccupythetimerequiredtopronouncethem.Thereader'sthoughtsinspectedthematleisuredrawingnewideasfromthemallowingcomparisonsfrommemoryorfromotherbooks. ①Toreadsilentlyistofreeyourmindtoreflecttoremembertoquestionandcompare.ThecognitivescientistMaryanneWolfcallsthisfreedomthesecretgiftoftimetothink.Athousandyearslatercriticsfearthatdigitaltechnologyhasputthisgiftindanger.TheInternet'sfloodofinformationtogetherwiththedistractionsofsocialmediathreatenstooverwhelmthespaceofreadingleavingusinwhatthejournalistNicholasCarrhascalledtheshallows.InCarr'sviewtheendlesstemptingbuzzoftheInternetendangersourverybeingOneofthegreatestdangerswefacehewritesaswegiveupcontrolovertheflowofourthoughtsandmemoriestoapowerfulelectronicsystemisaslowdamagetoourhumannessandourhumanity. ②There'snoquestionthatdigitaltechnologypresentschallengestothereadingbrain.Butseenfromahistoricalperspectivedigitalreadingandsilentreadinglooklikedifferencesofdegreeratherthanofkind.Totheextentthatdigitalreadingrepresentssomethingnewitspotentialcutsbothways.DonebadlytheInternetreducesustomindlessclickersracingnumblytothebottomofabottomlessfeedbutdonewellithasthepotentialtoexpandtheverycontemplative沉思的spacethatwehaveprizedinourselveseversincewelearnedtoreadwithoutmovingourlips. ③InthefifthcenturyB.C.Socratesworriedthatwritingwouldweakenhumanmemoryandstifle扼杀judgment.InfactasWolfnotesinher2007bookProustandtheSquidtheStoryandScienceoftheReadingBraintheoppositehappenedFacedwiththewrittenpagethereader'sbraindevelopsnewcapacities. ④TheInternetmaycauseourmindstowanderoffandyetaquicklookatthehistoryofbookssuggeststhatwehavebeenwanderingoffallalong.Whenwereadtheeyedoesnotprogresssteadilyalongthelineoftextitalternatesbetweensaccades﹣littlejumps﹣andbriefstopsnotunlikethemovementofthemouse'scursoracrossascreenofhypertext. ⑤It'struethatstudieshavefoundthatreadersgiventextonascreendoworseonrecallandcomprehensionteststhanreadersgiventhesametextonpaper.Buta2015studybytheGermaneducatorJohannesNaumannsuggeststheopposite.Hegaveagroupofhigh﹣schoolstudentsthejoboftrackingdowncertainpiecesofinformationonwebsiteshefoundthatthestudentswhoregularlydidresearchonlinewerebetteratthistaskthanstudentswhousedtheInternetmostlytosendemailchatandblog. ⑥Anewgenerationofdigitalwriterspreferstoincludeinteractivefeatures.The2014iPadnovelPrytellsthestoryofademolition爆破expertreturninghomefromthefirstGulfWar.Thestoryistoldintextphotographsvideoclipsandaudio.Itusesaninterface界面thatallowsyoutofollowtheactionandshiftbetweenlevelsofawareness.Asyoureadtextonthescreendescribingcharactersandplotyoudrawyourfingersapartandseeaphotographofthechiefcharacterhiseyesopeningontheworld.Pinchyourfingersshutandyouvisithistroubledunconsciouswordsandimagesracebyasifyouareinsidehismemory.Pryistheoppositeofashallowworkitswholeplayisbetweenthesurfaceandthedepthsofthehumanmind.Readingitisstimulating. 1InAlbertoManguel'sopinionsilentreading. A.isanabnormalthingtohumanconsciousness B.offersreaders'mindfreedomandtimetothink C.strengthensreaders'powerofmemoryandreflection D.allowsreaderstogainaninsightintobooksandwords 2Whyisdigitaltechnologyconsideredtohaveendangeredourbeing? A.Itpresentschallengestothereadingbrain. B.Itharmsourhumannessandhumanitygradually. C.Itisverylikelytoexpandourcontemplativespace. D.Itleavesourthoughtsandmemoriesoutofcontrol. 3ThesentenceThefearoftechnologyisnotnew.shouldbeplacedin. A.① B.② C.③ D.④ 4WhatcanweinferfromJohannesNaumann'sstudy? A.It'seasiertocollectinformationontheInternetthaninbooks. B.People'shabitofusingtheInternetinfluencestheirperformance. C.TheInternetisn'tsupposedtobeusedasatoolofentertainment. D.Paperreadingisbetterthanscreenreadinginimprovingcomprehension. 5The2014iPadnovelPryismentionedinthelastparagraphto. A.introducetheoccurrenceofareadingrevolution B.showthetechnologyemployedindigitalreading C.provedigitalreadingnotshallowbutattractive D.illustratetheimpactdigitalreadinghasonourlife 6Whatisprobablythebesttitleforthepassage? A.Thedeepspaceofdigitalreading B.Thetimelyarrivalofsilentreading C.Thedevelopmentoftraditionalreading D.Thepotentialdamageofelectronicbooks
函数fx＝xe-x在x∈[04]上的极大值为
已知双曲线＝1a＞0b＞0的一条渐近线方程为y＝-2x则此双曲线的离心率为
椭圆+y2＝1的长轴长为
MykidssitinGee'slivingroomandcautiouslyliftantiqueChristmasornaments饰品outofawell﹣lovedcardboardbox.Geestandsbesidethemquietly1eachtreasure.ShetellsmethatsheandTombuilttheirornament2piecebypieceduringeachyear'safter﹣Christmassale.She3asweleavewiththebox.Herprecioustreasuresgatheredoveralifetimehavefoundanew4. WefirstmetTomandGeeintheearlydaysofourmarriage.Someonehadbeen5ourgarbagecanstothegarageeachgarbagedayandJimandIhad6who.Thenonedaywe7himanelderlymanwholivedacrossthestreet. Ibakedcookiesandleftthemonastooloutsidethegaragewithathank﹣younote.Whenwegothomefromworkthatdayatypedletterhad8thegift.TheletterwasfromTomandexplainedhowhehadcometowalktheneighborhoodongarbagedayreturningcansforpeoplehe9knew.Backwhenhe'dbeenfightingawarIwasn't10toseehisyoungwifeGeehadfoundherselflivingalone.Neighborshadtakenthetimetohandlehergarbagecans11shedidn'thavetoandheneverforgot.Nowhe12itforwardbydoingthesameforallofus. Afewyearsafterwe'dmovedinTom13.Wephotocopiedthat14andattachedittooneofourownforGee.Wetoldherhow15Tomhadbeentousandhowwegrievedforher.Shewrotebackandtoldusshe16talkedtoTomeveryday.WhenGeeinvitedusovertolookthroughChristmasornamentsIrealizedhowharditmustbeto17withthatboxapieceofTom. JimandIagreeto18ourtreewithGee'sornamentsthisChristmasoutoftheboxthatis19inTom'shandwriting.MaybeI'lltalktohimjustasGeestilldoes.ThankyouI'llsayforteachinguswhatit20tobeaneighbor. 1A.confirming B.explaining C.revealing D.touching 2A.shelf B.basement C.art D.collection 3A.smiles B.weeps C.sighs D.hesitates 4A.home B.destination C.function D.chance 5A.distributing B.exposing C.returning D.attaching 6A.discovered B.wondered C.foreseen D.investigated 7A.spotted B.impressed C.acknowledged D.grasped 8A.answered B.replaced C.delivered D.rewarded 9A.especially B.thoroughly C.previously D.barely 10A.willing B.voluntary C.alive D.keen 11A.so B.before C.because D.if 12A.brought B.carried C.paid D.pushed 13A.survived B.withdrew C.retired D.died 14A.note B.gift C.letter D.treasure 15A.grateful B.close C.special D.superior 16A.still B.even C.just D.ever 17A.live B.finish C.go D.part 18A.supply B.manage C.decorate D.arm 19A.drafted B.labeled C.signed D.preserved 20A.reflects B.desires C.anticipates D.means
用数学归纳法证明“1-+-+…+＝n∈N*”第一步应验证的等式是从“n＝k”到“n＝k+l”左边需增加的代数式是
已知F为抛物线y2＝4x的焦点过点F且斜率为1的直线交抛物线于AB两点设|FA|＞|FB|则＝．
若函数fx＝mx3+2x2-3x-1存在单调递增区间则实数m的值可以为
已知抛物线y2＝4x过焦点F作斜率为k1的直线交抛物线于AB两点．1若|AB|＝5求k1．2过焦点F再作斜率为k2的直线交抛物线于CD两点且MN分别是线段ABCD的中点若k1+k2＝1证明直线MN过定点．
已知向量满足||＝1||＝||•＝0．若对每一确定的||最大值和最小值分别为mn则对任意m-n的最小值是．
函数fx＝4-2cosx的最小值是取得最小值时x的取值集合是．
复数z＝1-ii为虚数单位的虚部为
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