名词性从句讲义【主语从句及引导词】主语从句在复合句中作句子的主语。引导主语从句的词有从属连词that,whether,if；连接代词who,whoever,whom,what,whatever,whose,which；连接副词when,where,how,why等。【例句呈现】观察下列例句，指出其中所包含的主语从句及引导词:1.Whatisneededforalongtripiscarefulpreparation.该句中主语从句是______________，引导词为_____。2.ThatJayZhouwillcometomycityexciteseverybody.该句中主语从句是______________，引导词为_____。3.Whetherwewilltravelabroadornothasnotbeendecided.该句中主语从句是______________，引导词为_____。4.Whoeverknowsthesecretmustn’ttellothers.该句中主语从句是______________，引导词为_____。5.Itremainsapuzzlewhydinosaursdiedoutsuddenlylongtimeago.该句中主语从句是______________，引导词为_____。【观察总结】通过分析上面例句，同学们可能会发现上面第5句中的主语从句似乎比较隐蔽。其实，这也是主语从句的一种呈现方式，即：当一个句子主语过长时，可以用it作形式主语，而把真正的主语或主语从句后移至句子末尾，以保持句子的平衡。注意观察下列例句中的划线部分：Itisnotclearhowtheaccidenthappened.Itisnothardtounderstandwhyhedidsoatthattime.Itisapitythatyoushouldhavemadesuchacarelessmistake.Itisreportedthatmorethanthirtydeathswerecausedintheaccident.不难看出，虽然上面例句中都用it作形式主语，但句子结构却不尽相同。现将常见的由it作形式主语的句型总结如下：1.Itis+n.+that从句2.Itis+adj.+that从句，常见此类形容词有：important,necessary,clear,certain,natural,strange,obvious,likely,impossible,possible等。3．It+特殊动词+that从句Itseems/appears...that...似乎……Ithappened(tosb.)that...（某人）碰巧……4．It+be+过去分词+主语从句Itissaid/reported/believed/suggested/known/provedthat...【要点精讲】1.what与that引导主语从句观察下列例句，试着翻译例句并总结其规律。(1)Whatyoulackisself-confidence.译为：_____________________(2)Thatmoreandmorestudentsareadmittedintouniversitiesistrue.译为：_____________________(3)Whatisneededfortheprogramismorewisdom.译为：_____________________从上面例句可以看出，that引导主语从句时，在句中具有“两不”原则：一、不作句子成分；二、没有实际意义。当它引导的主语从句置于句首时，that不能省略；如果用it作形式主语，而把主语从句放在句末时，that可以省略。而what引导的从句则恰恰相反，what在从句中的作用为：一、作句子成分；二、除了起到引导从句的作用外还要承担具体的意义。【巩固练习】用what或that填空。(1)_____hetoldusthismorningwasjustalie.(2)_____isimportanttousisenoughtime.(3)Itworriesmymom_____sheisbeginningtogetalittlefat.(4)_____wecan’tgetseemsbetterthan_____wehave.2.whether与if引导主语从句如果主语从句置于句首，不能用if引导，此时，需用whether。但如果用it作形式主语，而把主语从句放在句末时，也可以用if引导。【巩固练习】用whether或if填空。(1)Itdoesn’tmatter_____hewillcomeornot.(2)_____we’llgocampingtomorrowdependsontheweather.(3)Itwasdoubtful_____TomreallysawSharon.(4)_____TomreallysawSharonwasdoubtful.3.其它引导词连接代词who,which,whom,whose有各自的具体意义，起连接作用，同时在从句中充当主语、宾语、表语、定语等；whoever,whatever,whichever在意义上更为强调，常译为“无论……”；连接副词when,where,why,how等也有各自的意义，起连接作用，并在从句中作状语。【高考链接】从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。1.Itisstillunderdiscussion_____theoldbusstationshouldbereplacedwithamodernhotelornot.(重庆2011)A.whetherB.whenC.whichD.where2.Thevillagershavealreadyknown_____we’lldoistorebuildthebridge.(江西2011)A.thisB.thatC.whatD.which3._____somepeopleregardasadrawbackisseenasaplusbymanyothers.(北京2010)A.WhetherB.WhatC.ThatD.How4.Itneveroccurredtome_____youcouldsucceedinpersuadinghimtochangehismind.(陕西2010)A.whichB.whatC.thatD.if5.Itisuncertain_____sideeffectthemedicinewillbringabout,althoughabouttwothousandpatientshavetakenit.(浙江2010)A.thatB.whatC.howD.whetherKey:【例句呈现】1．Whatisneededforalongtrip;what2．ThatJayZhouwillcometomycity;that3．Whetherwewilltravelabroadornot;whether4．Whoeverknowsthesecret;whoever5．whydinosaursdiedoutsuddenlylongtimeago;why【要点精讲】1.(1)你所缺乏的是自信。(2)越来越多的学生将被大学录取的消息是真实的。(3)这个项目所需要的是更多的智慧。【巩固练习】(1)What(2)What(3)that(4)What,what2.【巩固练习】(1)whether/if(2)Whether(3)whether/if(4)Whether【高考链接】1-5ACBCB
