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1名词性从句---------主语从句一、名词性从句概述：在句子中起名词作用的各种从句统称为名词性从句。根据它们在句中的语法作用，这类从句又可分为主语从句、同位语从句、表语从句和宾语从句。二、主语从句定义：在句中起主语作用的从句称为主语从句。引导主语从句的连接词主要有：单纯连词（that,whether/if）、连接代词(what,whatever,who,whoever,whom,whose,which,whichever等)和连接副词(when,where,why,how,whenever,wherever,however等)。1)that引导的主语从句（1）由连词that引导的主语从句:引导词that无含义/在句中不做成分/不可以省。例如：Thatyouwillwinthemedalseemsunlikely.你能得奖看起来不大可能。Thatlighttravelsinstraightlinesisknowntoall.众所周知，光沿直线传播。Thatyoudon’tlikehimisnoneofmybusiness.你不喜欢他不管我的事。（2）形式主语it替代主语从句位于句首，that引导真正的主语从句会放到句子的后面。常用的句式主要有如下几种：1.It+系动词+形容词+that从句。如：Itisnecessarythat…有必要……Itisclearthat…很清楚……Itislikelythat…很可能……Itisimportantthat…重要的是……类似的形容词还有：strange;natural;obvious;true;good;wonderful;possible;unlikely;quite;unusual;certain;evident;worth-while;surprising;interesting;astonishing,etc.例如：Itwasreallyastonishingthatherefusedtotalktoyou.Itisessentialthatheshouldbeherebytheweekend.2Itseemsobviousthatwecannotgoonlikethis.Itisnecessarythatyou（should）masterthecomputer.ItisimportantthatastudentlearnEnglishwell.It’sclearthattheybadlyneedhelp.Itislikelythatahurricanewillarrivesoon.知识拓展：在“Itisnecessary/important/surprising/strange/unthinkable/unbelievable/incredible+that从句”这类主语从句结构中，从句中谓语动词常用“（should）＋动词原形”，形式，即要用虚拟语气,should可省略。例如：Itisnecessarythatacollegestudent(should)masteroneortwoforeignlanguages.大学生掌握一两门外语是有必要的。Itisstrangethatyou(should)trustJane.很奇怪你竟然相信简。另外，需要注意的是，it作形式主语代替主语从句时，要注意和as引导的定语从句的区别。试比较：ItwasreportedthattheUSwasundertheterroristattack.Aswasreported,theUSwasundertheterroristattack.（2）常见用it作形式主语的复合句结构2.It+系动词+名词+that从句如：Itisafactthat…事实是……Itisgoodnewsthat………是好消息Itisaquestionthat………是个问题Itiscommonknowledgethat………是常识类似的名词还有：apity；awonder；agoodthing；nowonder；surprise等。例如：Itisamysterytomehowitallhappened.3Itiscommonknowledgethatthewhaleisnotafish.ItisnosurprisethatBobshouldhavewonthegame.It’sapitythatyoumissedthefilm.3.It+be+动词的过去分词+that从句如:Itissaidthat…据说……Itisreportedthat…据报道……Ithasbeenprovedthat…已证明……Itmustbeprovedthat…必须指出……类似的过去分词还有：known;estimated;expected;believed;thought;hoped;noted;discussed;required;decided;suggested;demanded;madeclear;foundout,etc.例如：Itisthoughtthatheisthebestplayer.Itisestimatedthatthevaseis2000yearsold.Ithasnotbeenmadeclearwhenthenewroadistobeopenedtotraffic.Itissaidthathewaskilledintheearthquake.4.It+特殊词+that从句。如：Itseems（happened/appears/doesn’tmatter/makesnodifference/occurred…）that…如：Itseemsthattheywillwinthegame.Itmakesnodifferencewhetherhewillattendthemeetingornot.ItdoesnotmatterifImissedmytrain.IthappenedthatIsawhimyesterday.2)用连词whether引导的主语从句whether有含义“是否”在句中不做成分/不可以省。注意：引导主语从句，不能用if，只能用whether。例如：Whetheryoulikehimornotisnoneofmybusiness.Whetherwewillholdapartyintheopenairtomorrowdependsontheweather.4Whethersheiscomingornotdoesn’tmattertoomuch.3)用连接代词引导的主语从句在由连接代词who,whose,whom,which,what,whoever,whomever,whichever,whatever引导的名词性从句中，其连接代词在句中起名词性作用，担当一定成分.例如：Whatyouneedismorepractice.WhatIwanttoknowisthis.Whateverwedoistoservethepeople.注：whatever/whoever的功用whatever,whoever在主语从句中不含疑问意义。它引导主语从句，并在从句中作主语、宾语、表语等。whatever=anythingthat;whoever=anyonewho。要注意和whatever,whoever引导的让步状语从句的区别。如：Whoeverbreaksthelawshouldbepunished.（主语从句）（＝Anyonewhobreaksthelawshouldbepunished.）Whoeverbreaksthelaw,heshouldbepunished.（让步状语从句）（＝Nomatterwhobreaksthelaw,heshouldbepunished.）4）用连接副词引导的主语从句用连接副词when,where,why,how,whenever,wherever,however等引导的主语从句从句(其连接副词有含义,在句中作状语。)例如:Whereweshouldleaveitisaproblem.Whentheywillcomehasn’tbeenmadepubic.温馨提示：如果主语从句是由连接代词what,whatever,whoever等引导的，表示的是一个具体的东西或人时，这样的主语从句不能用it作形式主语。Whatisworthdoingisworthdoingwell.Whateverwassaidherehasleftusmuchtoothink.Whoevercomeswillbewelcome.51）随堂练习1.Itdoesn’tmatter_________youturnrightorleftatthecrossing---bothroadsleadtothepark.A.whetherB.howC.ifD.when2.Itsuddenlyoccurredtohim________hehadlefthiskeysintheoffice.A.whetherB.whereC.whichD.that3.----We’veonlygotthissmallbookcase.Willthatdo?----No,_________Iamlookingforissomethingmuchbiggerandstronger.A.whoB.thatC.whatD.which4.Itdoesn’tmatter________youpaybycashorcreditcardinthisstore.A.howB.whetherC.whatD.why5.________thepollutingfactorywillberemovedfromthecityis,infact,________thecitizensaregladtosee.A.That;asB.As;whatC.That;whatD.What;that6.Idon’tsayIamagainstJackie’splan.Buttheproblemis___________hedoesfromtheseriousdiseasesoon.A.whatthatB.thatwhatC.whetherwhatD.whatwhether7.“When________leaveforJapan?”“When_______leaveforJapaniskeptsecret.”A.theywill;willtheyB.willthey;theywillC.theywill;theywillD.willthey;willthey8.Theylosttheirwayintheforest,and_________mademattersworsewasthatnightbegantofall.A.itB.whichC.thatD.what9.Ithascometomynotice________someofyouhavemissedtodoanythingwell.A.whatB.whichC.thatD.when10._______wearedoinghasneverbeendonebefore.A.ThatB.WhatC.WhichD.Whether62）家庭作业：1._____asmuchasone-fifthofalltimberharvestedisnotused.A.TheestimateB.TheestimatedC.TheyareestimatedD.Itisestimatedthat2._____somemammalscametoliveintheseaisnotknown.A.WhichB.SinceC.AlthoughD.How3._____wehaveachievedisattributedtotheguidanceofourparents.A.WhoeverB.WhateverC.HoweverD.That4._____wea