名词性从句概念：从句主语从句、表语从句、宾语从句等名词性从句的分类主语从句、表语从句、宾语从句、同位语从句主语从句Whatyouneedismorepractice.Thatsheisstillaliveisquiteobvious.Whenweshallhaveoursportsmeetisstillaquestion.Whetherornothewillgoisuptohimtodecide.在句中作主语，一般可置于谓语之前，但多数情况下，由it作形式主语，而把主语从句置于主句之后，可由what,that,when,whether等引导。a.It+be+形容词+that-从句Itisnecessarythat…有必要……Itisimportantthat…重要的是……Itisobviousthat…很明显……b.It+be+-ed分词+that-从句Itisbelievedthat…人们相信……Itisknowntoallthat…从所周知……Ithasbeendecidedthat…已决定……c.It+be+名词+that-从句Itiscommonknowledgethat………是常识Itisasurprisethat…令人惊奇的是……Itisafactthat…事实是……d.It+不及物动词+that-分句Itappearsthat…似乎……Ithappensthat…碰巧……Itoccurredtomethat…我突然想起……用it作形式主语的that-从句有以下四种不同的搭配关系：表语从句Thatiswhattheyshoulddo.Thatwashowtheyweredefeated.Shelookedasifshewasgoingtocry.在句中作表语，位于主句的系动词之后，可由that,what或其他连接代词或副词引导，也可由asif引导。宾语从句在主句中作及物动词或介词的宾语：1）由连接代词或副词引导，2）由关系代词型what等代词等引导，3）由that引导。1）由连接代词或副词引导，Eg:Couldyoutellmewheretherailwayis.2）由关系代词型what等代词等引导3）由that引导，常在以下的动词的否定和疑问之后4）在由引导的宾语从句中，要否定前置同位语从句Ihavenoideathatyouwerehere.Thenewsthatourbasketballteamhaswonthematchistruth.TheymarvelatthefactthatChinadiditallonitsown.跟在名词之后，进一步说明该名词的具体内容。引导同位语从句的名词有：fact,news,promise,idea,truth,hope,belief,thought,doubt等，连接词用that，不用which。以上两个句子that引导的从句都是同位语从句，它一般跟在某些名词如belief,fact,hope,idea,news,problem,possibility…的后面，用以说明或解释前面的名词。引导同位语从句的词最常见的是连词that,此外还有连接副词how,when,where,why等。eg:1Thepossibilitythatpeoplewouldhavetoshareroomswasnotmentioned.2IhavenoideawhenJakewillbeback.3Hecan’tanswerthequestionhowhegotthemoney.名词性从句应注意的若干要点1)所有名词性从句都应用陈述句的语序，例如：1．Whyhehasnotcomeisstillunknown.2．Heasked(me)whosebookthisis.2)当从句表达的是复数含义时，谓语动词则用复数形式，例如：1．Whetherhewillcomeornotmakesnodifference.2．WhatIsayandthinkarenobusinessofyours.3)主句与从句的时态应保留一致，例如：1．Hedidn’tknowwhyhewasscolded.2．Hetoldmethattheearthisround.4)suggest(建议)，order(命令)，insist(坚持要求)等接宾语从句时“(should)+动词原形”，例如：1．Isuggestedthathe(should)gorightaway.2.Theofficerorderedthatallthesoldiers(should)takepartinthecompetition.5)关于何时用that，何时用what的问题：that一般不充当句子成分，只作引导词，无实在的意义；what除起引导作用外，在句子中有意义，并充当一定的句子成分，例如：1．Thathewillcomehereisright.2．Whathesaidisquitereasonable.whetherwhether与与ifif均为“是否”的意思。但在下列情况下，均为“是否”的意思。但在下列情况下，whethewhetherr不能被不能被ifif所取代：所取代：1.whether引导主语从句（包括从句在句首的位置）应当用whether，不用if，如：Whetheritistrueremainsaproblem.Whetherhewillcome,Iamnotsure.2.引导表语从句用whether，不用if，如：Thequestioniswhetheryoushouldacceptit.3.whether可以引导从句作介词的宾语，而if则不能，如：I’mnotinterestedinwhetherthey’llgoornot.Itdependsonwhetherwehavegotenoughmoney.4.whether可以直接跟动词不定式连用，而if则不能，如：Ididn’tknowwhethertolaughortocry.Shehasn’tdecidedwhethertogoornot.5.引导同位语从句用whether，不用if，如：Thequestionwhetherhe’llattendthemeetingisessential.
