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1、NounClauses---ThesubjectclauseByDebbyGrammarWhatpartdoestheunderlinedpartserveasineachsentence?Atreehasfallenacrosstheroad.Youareastudent.Tofindyourwaycanbeaproblem.Smokingisbadforyou.“Howdoyoudo?”isagreeting.Whatshesaidisnotyetknown.Thatweshallbelateiscertain.Itiscerta
2、inthatweshallbelate.主语从句 （NounClausesastheSubject）定义：用作主语的从句叫主语从句，它是名词性从句之一。引导主语从句的连接词有：连词that,whether；连接代词who,what和which；连接副词when,where,how和why。主语从句的连接词连词that(无词义,不作成分,不能省略);whether(是否),if不能位于句首。Thathewillcomeandhelpusiscertain.Whetherwewillsucceedisstillaquestion.Itis
3、notknownifhewillcome.注意:已确定的事由that引导;没决定的事由whether引导.主语从句常用it作形式主语放句首因而我们常见到这种句式：It+be+n./adj/-ed从句（that,whether,etc.)例：It'sapitythatyoushouldhavetoleave.=Thatyoushouldhavetoleaveisapity.ItisgreatthatIhaveateacherlikeyou.=ThatIhaveateacherlikeyouisgreat.2)连接代词who，what，w
4、hich,whatever,whichever,whoever充当成分，有具体意义Whatseemseasytosomepeopleseemsdifficulttoothers.Whichsidewillwinisnotclear.3)连接副词when，where，how，why等。Whyhediditremainsamystery.Whentheywillstartisnotknownyet.Howhebecameagreatscientistisknowntousall.2.位置：主语从句可以前置，也可以后置。用it做形式主语，而
5、把主语从句，在句末，常用下面几种句型。1）It+be+表语+主语从句表语：（名词，形容词，过去分词）Itisafact(ashame,apity,goodnews…)that…Itisstilluncertainwhetherheiscomingornot.ItisanhonourthatIwasinvitedtoattendthemeeting.Itiscertainthatshewilldowellinherexam.ItistruethatItoldhereverything.ItissaidthatMr.Greenhasarr
6、ivedinBeijing.ItisreportedthatChinahassentanothermanmadeearthsatelliteintoorbit.2）It+不及物动词+主语从句Itseemed(happened,doesn’tmatter,hasturnedout)that…Ithappensthattheywereabsent.ItseemsthatAliceisnotcomingtothepartyatall.Itdoesn’tmatterwhethershewillcomeornot.Itmakesnodiffer
7、encewhereweshallhavethemeeting.3)It+及物动词（被动语态）+主语从句IthasbeendecidedthattheexhibitionwillnotopenonSundays.注意:1）主语从句在句首时，必须由连接词引导，不能省略这些连接词；但是如果用it做形式主语，而把主语从句放在句末时，从属连词that可以省略。4).用于Itisimportant/natural/necessary/impossiblethat...句型中,主语从句应使用虚拟语气,谓语动词用“should+动词原形”的形式,
8、should有时可以省略。5)在It+be+suggested/advised/ordered/requested/insisted/required中,that从句的谓语也应该用“should+动词原形”的形式,s
