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可用下列图示装置制取少量乙酸乙酯(酒精灯等在图中均已略去)。 反应结束后，振荡试管b，静置，观察到的现象是（）。
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下列操作或者说法错误的是
除去乙酸乙酯中的少量乙酸：加入乙醇和浓硫酸，使乙酸全部转化为乙酸乙酯
除去苯中的少量苯酚：加入NaOH溶液，振荡、静置分层后，除去水层
将铜丝在酒精灯上加热后，立即伸入无水乙醇中，铜丝恢复成原来的红色
提取溶解在水中的少量碘：加入CCl
4
，振荡、静置分层后，取出有机层再分离
哈三中某化学课外学习小组利用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空①试管a中需加入浓硫
可用下列图示装置制取少量乙酸乙酯酒精灯等在图中均已略去 试管b中加有饱和Na2C
可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空1试管a中需要加入浓硫酸冰醋酸和乙醇各2mL
可用下列图示装置制取少量乙酸乙酯酒精灯等在图中均已略去 试管a中需加入浓硫酸冰醋
2006全国Ⅱ卷可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空1试管a中需加入浓硫酸冰醋酸
实验题8分可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空:1试管a中需要加入浓硫酸冰醋酸和
可用下列图示装置制取少量乙酸乙酯酒精灯等在图中均已略去 为防止a中的液体在实验时
下列图示装置和原理均正确且能达到相应实验目的的是
用装置①验证石蜡可分解
用装置②除去甲烷中混有的少量乙烯
用装登③制取乙酸乙酯
用装置④分馏石油
可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空1试管a中需要加入浓硫酸冰醋酸和乙醇各2mL
可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空1试管a中需要加入浓硫酸冰醋酸和乙醇各2mL
可用如图所示装置制取少量乙酸乙酯酒精灯等在图中均已略去.请填空1试管a中需加入浓硫酸冰醋酸和乙醇各2
可用下列图示装置制取少量乙酸乙酯酒精灯等在图中均已略去 实验中加热试管a的目的是
下列实验能获得成功的是
用上图所示装置，无水乙酸和乙醇共热制取乙酸乙酯
将铜丝在酒精灯上加热后，立即伸入无水乙醇中，铜丝恢复原来的红色
用乙醇从碘水中萃取碘
淀粉用酸催化水解后的溶液加入新制银氨溶液，水浴加热，可看到有银镜出现
.下列实验能获得成功的是
用如图所示装置，无水乙酸和乙醇共热制取乙酸乙酯
将铜丝在酒精灯上加热后，立即伸入无水乙醇中， 铜丝恢复原来的红色
水和乙醇的混合液，可用蒸馏的方法使其分离
淀粉用酸催化水解后的溶液加入新制银氨溶液， 水浴加热，可观察到有银镜出现
可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空1试管a中需要加入浓硫酸冰醋酸和乙醇各2mL
哈三中某化学课外学习小组利用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空①试管a中需加入浓硫
哈三中某化学课外学习小组利用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空①试管a中需加入浓硫
可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空⑴试管a中需加入浓硫酸冰醋酸和乙醇各2mL正
可用图示装置制取少量乙酸乙酯酒精灯等在图中均已略去请填空1试管a中需要加入浓硫酸冰醋酸和乙醇各2mL
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某温度下FeOH3sCuOH2s分别在溶液中达到沉淀溶解平衡后改变溶液pH金属阳离子浓度的变化如图所示据图分析下列判断错误的是
从广义教育角度看教育者包括一切对他人施加的人从学校教育角度看教育者主要指
IamSergeyBrin!IwasborninMoscow.In1979whenIwas5myfamilyimmigratedtotheU.S.A.California.Irememberthatonmy9thbirthdayIgotmyfirstcomputerCommodore64.LaterIgraduatedwithhonorsintheUniversityofMarylandinMathematicsandIT.Themainfieldofmyscienceresearchwasthetechnologiesusedtocollectdatafromunsystematicsourcesaswellaslargequantitiesoftextsandsciencedata.IwastheauthorofdozensofarticlesinleadingAmericanacademicmagazines.Thegreatesteventinmylifehappenedwhenin1998Iwaspreparingforthedefense论文答辩ofmyDoctor’sdegreeinStanfordUniversity.TherethefatemadememeetLarryPage—ayoungcomputergenius.Larrybelongedtotheintellectual知识分子society.LarryandIquicklybecamefriendswhenweworkedtogether.WeweresearchingdayandnightontheInternet.Wewerefindingalotofinformationbutwiththefeelingwestillcouldn’tfindenoughofwhatwewerelookingfor.Naturallytheideaforasearchenginethatwouldallowspecificinformationtobefoundintheendlesspoolofdatawasbornlikeitcametous.Itwasn’tourplansbutwegaveuptheeducationattheuniversity.Youknowthenextpartmaybe—wemanagedtoturnanordinarygarageinMeploParkCaliforniatheU.S.A.intoourfirstofficeinwhichGooglewasborn.WithexcitementwetypedthenameofthethingwhichwecreatedwithloveonSeptember14th1998—www.Google.com.Nowafterthoseyearsweboughtthisgarage.Asasymbolitwillalwaysremindusthateverythingispossible.WhydidtheyfoundGoogle
Amiddle-agedmanwithalongbeardwasarrestedbythepolicefordisorderlyconductandpropertydamage.Morechargesmightheaddedlatersaidapoliceofficer.ThemanidentifiedasBillWildcheckedintotheMotelFivelastnightaboutanhouraftersunset.Tellingtheclerkthathewouldbestayingfournightshepaidcashinadvance.ShesaidthatthenearestgrocerystorewasJohn-Johnswhichwasonlytwoblocksaway.ThepolicesaidthatWildwenttoJohn-Johnsandpurchasedthreegallonsofhoneyandfourgallonsofchocolatesyrup糖浆.Thecheckeraskedhimwhattheoccasionwas.HerepliedI’mtryingtobecomeasweeterperson.Thecheckersmiledatthejoke.Wilddrovebacktothemotel.Heopenedallsevencontainersandpouredthemintothebathtub.Headdedwarmwatertothemix.Thenheplacedhisboomboxonthebathroomfloornexttothetub.Hetunedtheradiotoanoperastation.Hegotundressedhoppedintothetubandstartedsingingloudlywiththemusic.Fifteenminuteslaterthelodgersintheroomnextdoorphonedtheclerk.ShebangedonWild’sdoorbuthekeptsinging.Shephonedhisroombuthedidn’tanswer.Thenshecalledthepolicewhoarrivedquickly.Wellatleasthepaidinadvancesaidtheclerk.Thatmoneywillhelppayfortheplumber管子工.Thebathtubdrainwascompletelyclogged阻塞.Thetubremainedfullofchocolateandhoney.Youjustneverknowaboutpeoplesaidtheclerk.Heseemedsoniceandfriendly.Who’dhavethoughthewasabathtub-singingnutThepolicesaidthiswasthethirdtimethatWildhadbeenarrestedforthiskindofbehavior.WhatdoyouthinkofBillWildWhyPleaseanswerwithin30words
奥苏贝尔认为学校情境中的成就动机主要由三方面的内驱力组成体现的是以求知作为目标从知识的获得中得到满足是学习的内部动机
AB两种烃组成的混合物当它们的总质量一定时无论AB以何种比例混合完全燃烧生成的CO2的质量都相等符合这一条件的组合有①同分异构体②同系物③具有相同的最简式④含碳的质量分数相等其中正确的是
Theevidenceforharmonymaynotbeobviousinsomefamilies.Butitseemsthatfouroutoffiveyoungpeoplenowgetonwiththeirparentswhichistheoppositeofthepopularly-heldimage形象ofunhappyteenagerslockedintheirroomafterendlessfamilyquarrels.Animportantnewstudyintoteenageattitudessurprisinglyshowsthattheirfamilylifeismoreharmoniousthanithaseverbeeninthepast.Weweresurprisedbyjusthowpositivetoday’syoungpeopleseemtobeabouttheirfamiliessaidonememberoftheresearchteamThey’reexpectedtoberebellious叛逆的andselfishbutactuallytheyhaveotherthingsontheirminds:theywantacarandmaterialgoodsandtheyworryaboutwhetherschoolisservingthemwell.There’smorenegotiation商议anddiscussionbetweenparentsandchildrenandchildrenexpecttotakepartinthefamilydecision-makingprocess.Theydon’twanttorocktheboat.Soitseemsthatthisgenerationofparentsismuchmorelikelythanparentsof30yearsagototreattheirchildrenasfriends.Myparentsarehappytodiscussthingswithmeandwillingtolistentomesays17-year-oldDanielLazallIalwaystellthemwhenI’mgoingoutclubbing.AslongastheyknowwhatI’mdoingthey’refinewithit.SusanCromewhoisnow21agrees.Lookingbackonthelast10yearstherewasalotofwhatyoucouldcallnegotiation.ForexampleaslongasI’ddoneallmyhomeworkIcouldgooutonaSaturdaynight.ButIthinkmygrandparentswerealotstricterwithmyparentsthanthat.Maybethispositiveviewoffamilylifeshouldnotbeunexpected.Itispossiblethattheideaofteenagerebellionisnotrootedinrealfacts.AresearchercommentsOursurprisethatteenagerssaytheygetalongwellwiththeirparentscomesbecauseofabriefperiodinoursocialhistorywhenteenagerswereregardedasdifferentbeings.Butthatideaofrebellingandbreakingawayfromtheirparentsreallyonlyhappenedduringthatonetimeinthe1960swheneveryonerebelled.Thenormalsituationthroughouthistoryhasbeenasmoothchangefromhelpingoutwiththefamilybusinesstotakingitover./Comparedwithparentsof30yearsagotoday’sparents______.
Fromthehealthpointofviewwearelivinginamarvelousage.Weareimmunizedfrombirthagainstmanyofthemostdangerousdiseases.Alargenumberofoncefatalillnessescannowbecuredbymoderndrugsandsurgery.Itisalmostcertainthatonedayremedieswillbefoundforthemoststubbornremainingdiseases.Theexpectationoflifehasincreasedenormously.Butthoughthepossibilityoflivingalongandhappylifeisgreaterthaneverbeforeeverydaywewitnesstheincredibleslaughterofmenwomenandchildrenontheroads.Manversusthemotorcar!Itisanever-endingbattlewhichmanislosing.Thousandsofpeopleovertheworldarekilledorhorriblykilledeachyearandwearequietlysittingbackandlettingithappen.Ithasbeenrightlysaidthatwhenamanissittingbehindasteeringwheelhiscarbecomestheextensionofhispersonality.Thereisnodoubtthatthemotorcaroftenbringsoutaman’sveryworstqualities.Peoplewhoarenormallyquietandpleasantmaybecomeunrecognizablewhentheyarebehindasteering-wheel.Theysweartheyareill-manneredandaggressivewillfulastwo-year-oldsandutterlyselfish.Alltheirhiddenfrustrationsdisappointmentsandjealousiesseemtobebroughttothesurfacebytheactofdriving.Thesurprisingthingisthatsocietysmilessobenignlyonthemotoristandseemstocondonehisbehaviour.Everythingisdoneforhisconvenience.Citiesareallowedtobecomealmostuninhabitablebecauseofheavytraffic;townsaremadeuglybyhugecarparks;thecountrysideisdesecratedbyroadnetworks;andthemassannualslaughterbecomesnothingmorethanastatistictobeconvenientlyforgotten.Itishightimeaworldcodewerecreatedtoreducethissenselesswasteofhumanlife.Withregardtodrivingthelawsofsomecountriesarenotoriouslylaxandeventhestrictestarenotstrict:enough.Acodewhichwasuniversallyacceptedcouldonlyhaveadramaticallybeneficialeffectontheaccidentrate.Hereareafewexamplesofsomeofthethingsthatmightbedone.Thedrivingtestshouldbestandardizedandmadefarmoredifficultthanitis;allthedriversshouldbemadetotakeatesteverythreeyearsorso;theageatwhichyoungpeopleareallowedtodriveanyvehicleshouldheraisedtoatleast21;allvehiclesshouldbeputthroughstringentannualtestsforsafety.Eventhesmallestamountofalcoholinthebloodcanimpairaperson’sdrivingability.Presentdrinkinganddrivinglawswheretheyexistshouldhemadmuchstricter.Maximumandminimumspeedlimitsshouldbeimposedonallroads.GovernmentsshouldlaydownsafetyspecificationsformanufacturersashasbeendoneintheUSA.Alladvertisingstressingpowerandperformanceshouldbebanned.Thesemeasuresmaysoundinordinatelyharsh.Butsurelynothingshouldbeconsideredassevereifitresultsinreducingtheannualtollofhumanlife.Afteralltheworldisforhumanbeingsnotmotorcars.Whatdoestheauthorthinkofsocietytowardmotorists
下列热化学方程式或离子方程式中正确的是
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教育的技巧并不在于能预见到课堂的所有细节而是在于根据当时的具体情况捕捉一些有价值的细节巧妙地在学生不知不觉之中作出相应的调整和变动——苏霍姆林斯基分析教学细节的重要意义
Howshouldoneinvestasumofmoneyinthesedaysofinflation通货膨胀Leftinabankitwillhardlykeepitsvaluehoweverhightheinterestrateis.OnlyabravemanoraveryrichonedarestobuyandsellontheStockMarket.Todayitseemsthatoneofthebestwaystoprotectyoursavingsandevenincreaseyourwealthistobuybeautifulobjectsfromthepast.HereIamgoingtooffersomeadviceoncollectingantiqueclockswhichIpersonallyconsiderareamongthemostinterestingofantiques.Isometimeswonderwhatabeingfromanotherplanetmightreportbackaboutourwayoflife.TheplanetEarthisruledbyamysteriouscreaturethatsitsorstandsinaroomandmakesastrangetickingsound.Ithasafacewithtwelveblackmarksandtwohands.Mencandonothingwithoutitspermissionanditfastensitsyoungroundpeople’swristssothateverywheremengotheyarestillunderitscontrol.ThiscreatureistherealmasterofEarthandmenareitsslaves.Whetherornotweareslavesoftimetodaydependsonourcultureandpersonalitybutitisbelievedthatmanyyearsagokingskeptspecialslavestotellthetime.Certainmenwereverycleveratmeasuringthetimeofdayaccordingtothebeatingoftheirownhearts.Theyweremadetostandinafixedplaceandeveryhourorsowouldshoutthetime.Soitseemsthatthefirstclockswerehumanbeings.Howevermenquicklyfoundmoreconvenientandreliablewaysoftellingthetime.Theylearnedtousetheshadowscastbythesun.Theymarkedthehoursoncandlesusedsandinhourglassesandinventedwater-clocks.Indeedanyseriousstudentofantiquesshouldspendasmuchtimeaspossiblevisitingpalacesstatelyhomesandmuseumstoseesomeofthefinestexamplesofclocksfromthepast.Antiqueclockscouldbeveryexpensivebutoneofthejoysofcollectingclocksisthatitisstillpossibletofindquitecheaponesforyourownhome.AfterallifyouaregoingtoberuledbythetimewhynotinvestinairantiqueclockandperhapsmakeafutureprofitWhichofthefollowingisNOTmentionedasawaytomeasurethetime
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鸡没有汗腺夏天只能依赖“喘息”调节体温鸡过度呼出CO2会使下列平衡向左移动导致蛋壳变薄即下“软壳蛋”使养鸡专业户蒙受经济损失 澳大利亚学者研究发现夏季给鸡喂食下列某种饮料会使蛋壳变厚这种饮料是
Amiddle-agedmanwithalongbeardwasarrestedbythepolicefordisorderlyconductandpropertydamage.Morechargesmightheaddedlatersaidapoliceofficer.ThemanidentifiedasBillWildcheckedintotheMotelFivelastnightaboutanhouraftersunset.Tellingtheclerkthathewouldbestayingfournightshepaidcashinadvance.ShesaidthatthenearestgrocerystorewasJohn-Johnswhichwasonlytwoblocksaway.ThepolicesaidthatWildwenttoJohn-Johnsandpurchasedthreegallonsofhoneyandfourgallonsofchocolatesyrup糖浆.Thecheckeraskedhimwhattheoccasionwas.HerepliedI’mtryingtobecomeasweeterperson.Thecheckersmiledatthejoke.Wilddrovebacktothemotel.Heopenedallsevencontainersandpouredthemintothebathtub.Headdedwarmwatertothemix.Thenheplacedhisboomboxonthebathroomfloornexttothetub.Hetunedtheradiotoanoperastation.Hegotundressedhoppedintothetubandstartedsingingloudlywiththemusic.Fifteenminuteslaterthelodgersintheroomnextdoorphonedtheclerk.ShebangedonWild’sdoorbuthekeptsinging.Shephonedhisroombuthedidn’tanswer.Thenshecalledthepolicewhoarrivedquickly.Wellatleasthepaidinadvancesaidtheclerk.Thatmoneywillhelppayfortheplumber管子工.Thebathtubdrainwascompletelyclogged阻塞.Thetubremainedfullofchocolateandhoney.Youjustneverknowaboutpeoplesaidtheclerk.Heseemedsoniceandfriendly.Who’dhavethoughthewasabathtub-singingnutThepolicesaidthiswasthethirdtimethatWildhadbeenarrestedforthiskindofbehavior.WhichsentenceinthepassagecanbereplacedbythefollowingoneHelookssokindandamicablethatwehadneverthoughthewasamadmanwholikestosinginbathtub.
德育过程从本质上说就是统一过程
Theevidenceforharmonymaynotbeobviousinsomefamilies.Butitseemsthatfouroutoffiveyoungpeoplenowgetonwiththeirparentswhichistheoppositeofthepopularly-heldimage形象ofunhappyteenagerslockedintheirroomafterendlessfamilyquarrels.Animportantnewstudyintoteenageattitudessurprisinglyshowsthattheirfamilylifeismoreharmoniousthanithaseverbeeninthepast.Weweresurprisedbyjusthowpositivetoday’syoungpeopleseemtobeabouttheirfamiliessaidonememberoftheresearchteamThey’reexpectedtoberebellious叛逆的andselfishbutactuallytheyhaveotherthingsontheirminds:theywantacarandmaterialgoodsandtheyworryaboutwhetherschoolisservingthemwell.There’smorenegotiation商议anddiscussionbetweenparentsandchildrenandchildrenexpecttotakepartinthefamilydecision-makingprocess.Theydon’twanttorocktheboat.Soitseemsthatthisgenerationofparentsismuchmorelikelythanparentsof30yearsagototreattheirchildrenasfriends.Myparentsarehappytodiscussthingswithmeandwillingtolistentomesays17-year-oldDanielLazallIalwaystellthemwhenI’mgoingoutclubbing.AslongastheyknowwhatI’mdoingthey’refinewithit.SusanCromewhoisnow21agrees.Lookingbackonthelast10yearstherewasalotofwhatyoucouldcallnegotiation.ForexampleaslongasI’ddoneallmyhomeworkIcouldgooutonaSaturdaynight.ButIthinkmygrandparentswerealotstricterwithmyparentsthanthat.Maybethispositiveviewoffamilylifeshouldnotbeunexpected.Itispossiblethattheideaofteenagerebellionisnotrootedinrealfacts.AresearchercommentsOursurprisethatteenagerssaytheygetalongwellwiththeirparentscomesbecauseofabriefperiodinoursocialhistorywhenteenagerswereregardedasdifferentbeings.Butthatideaofrebellingandbreakingawayfromtheirparentsreallyonlyhappenedduringthatonetimeinthe1960swheneveryonerebelled.Thenormalsituationthroughouthistoryhasbeenasmoothchangefromhelpingoutwiththefamilybusinesstotakingitover./Whatisthepopularimageofteenagerstoday
Theevidenceforharmonymaynotbeobviousinsomefamilies.Butitseemsthatfouroutoffiveyoungpeoplenowgetonwiththeirparentswhichistheoppositeofthepopularly-heldimage形象ofunhappyteenagerslockedintheirroomafterendlessfamilyquarrels.Animportantnewstudyintoteenageattitudessurprisinglyshowsthattheirfamilylifeismoreharmoniousthanithaseverbeeninthepast.Weweresurprisedbyjusthowpositivetoday’syoungpeopleseemtobeabouttheirfamiliessaidonememberoftheresearchteamThey’reexpectedtoberebellious叛逆的andselfishbutactuallytheyhaveotherthingsontheirminds:theywantacarandmaterialgoodsandtheyworryaboutwhetherschoolisservingthemwell.There’smorenegotiation商议anddiscussionbetweenparentsandchildrenandchildrenexpecttotakepartinthefamilydecision-makingprocess.Theydon’twanttorocktheboat.Soitseemsthatthisgenerationofparentsismuchmorelikelythanparentsof30yearsagototreattheirchildrenasfriends.Myparentsarehappytodiscussthingswithmeandwillingtolistentomesays17-year-oldDanielLazallIalwaystellthemwhenI’mgoingoutclubbing.AslongastheyknowwhatI’mdoingthey’refinewithit.SusanCromewhoisnow21agrees.Lookingbackonthelast10yearstherewasalotofwhatyoucouldcallnegotiation.ForexampleaslongasI’ddoneallmyhomeworkIcouldgooutonaSaturdaynight.ButIthinkmygrandparentswerealotstricterwithmyparentsthanthat.Maybethispositiveviewoffamilylifeshouldnotbeunexpected.Itispossiblethattheideaofteenagerebellionisnotrootedinrealfacts.AresearchercommentsOursurprisethatteenagerssaytheygetalongwellwiththeirparentscomesbecauseofabriefperiodinoursocialhistorywhenteenagerswereregardedasdifferentbeings.Butthatideaofrebellingandbreakingawayfromtheirparentsreallyonlyhappenedduringthatonetimeinthe1960swheneveryonerebelled.Thenormalsituationthroughouthistoryhasbeenasmoothchangefromhelpingoutwiththefamilybusinesstotakingitover./Whatisthepassagemainlyabout
Howshouldoneinvestasumofmoneyinthesedaysofinflation通货膨胀Leftinabankitwillhardlykeepitsvaluehoweverhightheinterestrateis.OnlyabravemanoraveryrichonedarestobuyandsellontheStockMarket.Todayitseemsthatoneofthebestwaystoprotectyoursavingsandevenincreaseyourwealthistobuybeautifulobjectsfromthepast.HereIamgoingtooffersomeadviceoncollectingantiqueclockswhichIpersonallyconsiderareamongthemostinterestingofantiques.Isometimeswonderwhatabeingfromanotherplanetmightreportbackaboutourwayoflife.TheplanetEarthisruledbyamysteriouscreaturethatsitsorstandsinaroomandmakesastrangetickingsound.Ithasafacewithtwelveblackmarksandtwohands.Mencandonothingwithoutitspermissionanditfastensitsyoungroundpeople’swristssothateverywheremengotheyarestillunderitscontrol.ThiscreatureistherealmasterofEarthandmenareitsslaves.Whetherornotweareslavesoftimetodaydependsonourcultureandpersonalitybutitisbelievedthatmanyyearsagokingskeptspecialslavestotellthetime.Certainmenwereverycleveratmeasuringthetimeofdayaccordingtothebeatingoftheirownhearts.Theyweremadetostandinafixedplaceandeveryhourorsowouldshoutthetime.Soitseemsthatthefirstclockswerehumanbeings.Howevermenquicklyfoundmoreconvenientandreliablewaysoftellingthetime.Theylearnedtousetheshadowscastbythesun.Theymarkedthehoursoncandlesusedsandinhourglassesandinventedwater-clocks.Indeedanyseriousstudentofantiquesshouldspendasmuchtimeaspossiblevisitingpalacesstatelyhomesandmuseumstoseesomeofthefinestexamplesofclocksfromthepast.Antiqueclockscouldbeveryexpensivebutoneofthejoysofcollectingclocksisthatitisstillpossibletofindquitecheaponesforyourownhome.AfterallifyouaregoingtoberuledbythetimewhynotinvestinairantiqueclockandperhapsmakeafutureprofitThepurposeofthepassageis______.
Howshouldoneinvestasumofmoneyinthesedaysofinflation通货膨胀Leftinabankitwillhardlykeepitsvaluehoweverhightheinterestrateis.OnlyabravemanoraveryrichonedarestobuyandsellontheStockMarket.Todayitseemsthatoneofthebestwaystoprotectyoursavingsandevenincreaseyourwealthistobuybeautifulobjectsfromthepast.HereIamgoingtooffersomeadviceoncollectingantiqueclockswhichIpersonallyconsiderareamongthemostinterestingofantiques.Isometimeswonderwhatabeingfromanotherplanetmightreportbackaboutourwayoflife.TheplanetEarthisruledbyamysteriouscreaturethatsitsorstandsinaroomandmakesastrangetickingsound.Ithasafacewithtwelveblackmarksandtwohands.Mencandonothingwithoutitspermissionanditfastensitsyoungroundpeople’swristssothateverywheremengotheyarestillunderitscontrol.ThiscreatureistherealmasterofEarthandmenareitsslaves.Whetherornotweareslavesoftimetodaydependsonourcultureandpersonalitybutitisbelievedthatmanyyearsagokingskeptspecialslavestotellthetime.Certainmenwereverycleveratmeasuringthetimeofdayaccordingtothebeatingoftheirownhearts.Theyweremadetostandinafixedplaceandeveryhourorsowouldshoutthetime.Soitseemsthatthefirstclockswerehumanbeings.Howevermenquicklyfoundmoreconvenientandreliablewaysoftellingthetime.Theylearnedtousetheshadowscastbythesun.Theymarkedthehoursoncandlesusedsandinhourglassesandinventedwater-clocks.Indeedanyseriousstudentofantiquesshouldspendasmuchtimeaspossiblevisitingpalacesstatelyhomesandmuseumstoseesomeofthefinestexamplesofclocksfromthepast.Antiqueclockscouldbeveryexpensivebutoneofthejoysofcollectingclocksisthatitisstillpossibletofindquitecheaponesforyourownhome.AfterallifyouaregoingtoberuledbythetimewhynotinvestinairantiqueclockandperhapsmakeafutureprofitAccordingtothepassagecollectingantiqueclocks______.
Fromthehealthpointofviewwearelivinginamarvelousage.Weareimmunizedfrombirthagainstmanyofthemostdangerousdiseases.Alargenumberofoncefatalillnessescannowbecuredbymoderndrugsandsurgery.Itisalmostcertainthatonedayremedieswillbefoundforthemoststubbornremainingdiseases.Theexpectationoflifehasincreasedenormously.Butthoughthepossibilityoflivingalongandhappylifeisgreaterthaneverbeforeeverydaywewitnesstheincredibleslaughterofmenwomenandchildrenontheroads.Manversusthemotorcar!Itisanever-endingbattlewhichmanislosing.Thousandsofpeopleovertheworldarekilledorhorriblykilledeachyearandwearequietlysittingbackandlettingithappen.Ithasbeenrightlysaidthatwhenamanissittingbehindasteeringwheelhiscarbecomestheextensionofhispersonality.Thereisnodoubtthatthemotorcaroftenbringsoutaman’sveryworstqualities.Peoplewhoarenormallyquietandpleasantmaybecomeunrecognizablewhentheyarebehindasteering-wheel.Theysweartheyareill-manneredandaggressivewillfulastwo-year-oldsandutterlyselfish.Alltheirhiddenfrustrationsdisappointmentsandjealousiesseemtobebroughttothesurfacebytheactofdriving.Thesurprisingthingisthatsocietysmilessobenignlyonthemotoristandseemstocondonehisbehaviour.Everythingisdoneforhisconvenience.Citiesareallowedtobecomealmostuninhabitablebecauseofheavytraffic;townsaremadeuglybyhugecarparks;thecountrysideisdesecratedbyroadnetworks;andthemassannualslaughterbecomesnothingmorethanastatistictobeconvenientlyforgotten.Itishightimeaworldcodewerecreatedtoreducethissenselesswasteofhumanlife.Withregardtodrivingthelawsofsomecountriesarenotoriouslylaxandeventhestrictestarenotstrict:enough.Acodewhichwasuniversallyacceptedcouldonlyhaveadramaticallybeneficialeffectontheaccidentrate.Hereareafewexamplesofsomeofthethingsthatmightbedone.Thedrivingtestshouldbestandardizedandmadefarmoredifficultthanitis;allthedriversshouldbemadetotakeatesteverythreeyearsorso;theageatwhichyoungpeopleareallowedtodriveanyvehicleshouldheraisedtoatleast21;allvehiclesshouldbeputthroughstringentannualtestsforsafety.Eventhesmallestamountofalcoholinthebloodcanimpairaperson’sdrivingability.Presentdrinkinganddrivinglawswheretheyexistshouldhemadmuchstricter.Maximumandminimumspeedlimitsshouldbeimposedonallroads.GovernmentsshouldlaydownsafetyspecificationsformanufacturersashasbeendoneintheUSA.Alladvertisingstressingpowerandperformanceshouldbebanned.Thesemeasuresmaysoundinordinatelyharsh.Butsurelynothingshouldbeconsideredassevereifitresultsinreducingtheannualtollofhumanlife.Afteralltheworldisforhumanbeingsnotmotorcars.WhichofthefollowingisNOTmentionedasawayagainsttrafficaccidents
用质量均为100.0g的铜作电极电解硝酸银溶液电解一段时间后两电极的质量相差28.0g则阴极的质量为
在一个密闭容器中盛有11gX气体X的摩尔质量为44g·mol-1时压强为1×104Pa如果在相同温度下把更多的气体X充入容器使容器内的压强增至5×104Pa这时容器内气体X的分子数约为
久置空气中会发生颜色变化但颜色变化不是由于跟氧气反应引起的物质是
IamSergeyBrin!IwasborninMoscow.In1979whenIwas5myfamilyimmigratedtotheU.S.A.California.Irememberthatonmy9thbirthdayIgotmyfirstcomputerCommodore64.LaterIgraduatedwithhonorsintheUniversityofMarylandinMathematicsandIT.Themainfieldofmyscienceresearchwasthetechnologiesusedtocollectdatafromunsystematicsourcesaswellaslargequantitiesoftextsandsciencedata.IwastheauthorofdozensofarticlesinleadingAmericanacademicmagazines.Thegreatesteventinmylifehappenedwhenin1998Iwaspreparingforthedefense论文答辩ofmyDoctor’sdegreeinStanfordUniversity.TherethefatemadememeetLarryPage—ayoungcomputergenius.Larrybelongedtotheintellectual知识分子society.LarryandIquicklybecamefriendswhenweworkedtogether.WeweresearchingdayandnightontheInternet.Wewerefindingalotofinformationbutwiththefeelingwestillcouldn’tfindenoughofwhatwewerelookingfor.Naturallytheideaforasearchenginethatwouldallowspecificinformationtobefoundintheendlesspoolofdatawasbornlikeitcametous.Itwasn’tourplansbutwegaveuptheeducationattheuniversity.Youknowthenextpartmaybe—wemanagedtoturnanordinarygarageinMeploParkCaliforniatheU.S.A.intoourfirstofficeinwhichGooglewasborn.WithexcitementwetypedthenameofthethingwhichwecreatedwithloveonSeptember14th1998—www.Google.com.Nowafterthoseyearsweboughtthisgarage.Asasymbolitwillalwaysremindusthateverythingispossible.SergeyBrinactuallygraduatedfrom______.
短周期元素形成的常见非金属固体单质A与常见金属单质B在加热条件下反应生成化合物CC与水反应生成白色沉淀D和气体ED既能溶于强酸也能溶于强碱E在足量空气中燃烧产生刺激性气体GG在大气中能导致酸雨的形成E被足量氢氧化钠溶液吸收得到无色溶液F溶液F在空气中长期放置发生反应生成物之一为HH与过氧化钠的结构和化学性质相似其溶液显黄色 请回答下列问题 组成单质A的元素位于周期表中第周期第族
短周期元素形成的常见非金属固体单质A与常见金属单质B在加热条件下反应生成化合物CC与水反应生成白色沉淀D和气体ED既能溶于强酸也能溶于强碱E在足量空气中燃烧产生刺激性气体GG在大气中能导致酸雨的形成E被足量氢氧化钠溶液吸收得到无色溶液F溶液F在空气中长期放置发生反应生成物之一为HH与过氧化钠的结构和化学性质相似其溶液显黄色 请回答下列问题 H的溶液与稀硫酸反应产生的现象为
烃是有机化学中一类重要的有机物烯烃中C=C键由一个σ键和一个π键组成其中σ键组成物质的基本骨架它能旋转而π键比σ键弱不能旋转 二烯烃与单烯烃或炔烃类物质可发生14-成环加成反应生成六元环状化合物如 将太阳能有效地转化为其他形式的能量是解决化石燃料耗尽后世界能源问题的关键 有人提出以降冰片二烯BCD为介质将太阳能转化为其他形式的能量的方法是首先让BCD吸收太阳光BCD转化为其同分异构体四环烷QC然后QC在催化剂的作用下重新转化为BCD并放出能量生成的BCD可循环使用BCD可由一分子环戊二烯和一分子乙炔经二聚反应制得BCD吸收光能发生光化学反应生成QC的过程中未发生σ键的断裂 根据以上信息请回答下列问题 比较BCD和QC能量的相对高低BCDQC填＞＜或=
Fromchildhoodtooldagewealluselanguageasameansofbroadeningourknowledgeofourselvesandtheworldaboutus.Whenhumansfirst16theywerelikenewbornchildrenunabletousethis17tool.Yetoncelanguagedevelopedthepossibilitiesforhumankind’sfuture18andculturalgrowthincreased.Manylinguistsbelievethatevolutionis19forourabilitytoproduceanduselanguage.They20thatourhighlyevolvedbrainprovidesus21aninnatelanguageabilitynotfoundinlower22.Proponentsofthisinnatenesstheorysaythatour23forlanguageisinbornbutthatlanguageitselfdevelopsgradually24afunctionofthegrowthofthebrainduringchildhood.Thereforetherearecritical25timesforlanguagedevelopment.Current26oftheinnatenesstheoryaremixed;howeverevidencesupportingtheexistenceofsomeinnateabilitiesisundeniable.27moreandmoreschoolsarediscoveringthatforeignlanguagesarebesttaughtin28grades.Youngchildrenoftencanlearnseverallanguagesbybeing29tothemwhileadultshaveamuchhardertimelearninganotherlanguageoncethe30oftheirfirstlanguagehavebecomefirmlyfixed.31someaspectsoflanguageareundeniablyinnatelanguagedoesnotdevelopautomaticallyinavacuum.Childrenwhohavebeen32fromotherhumanbeingsdonotpossesslanguage.Thisdemonstratesthat33withotherhumanbeingsisnecessaryforproperlanguagedevelopment.Somelinguistsbelievethatthisisevenmorebasictohumanlanguage34thananyinnatecapacities.Thesetheoristsviewlanguageasimitativelearnedbehavior.35childrenlearnlanguagefromtheirparentsbyimitatingthem.Parentsgraduallyshapetheirchild’slanguageskillsbypositivelyreinforcingpreciseimitationsandnegativelyreinforcingimpreciseones.Ⅱ．完形填空/Cloze阅读下列短文掌握其大意然后从每小题所给的四个选项ABCD中选出最佳选项
如下图所示烧杯甲中盛放100mL6mol·L-1的盐酸烧杯乙中盛放100mL冷水现向烧杯甲的溶液中放入25gNaOH固体同时向烧杯乙中放入NH4NO3固体搅拌使之溶解 1A瓶中气体的颜色简述理由 2B瓶中气体的颜色简述理由
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