主语从句是一个重要的语法点

1主语从句是一个重要的语法点，主语从句是中学阶段的重点语法项目,也是高考的热点之一。为使同学们更好地掌握其用法,本文对主语从句语法做了一个详细的梳理，帮助大家梳理主语从句的语序，连接词的选用等内容，对于it构成的主语从句做了详细的解释。以便帮助大家掌握这一重要知识点。一.主语从句的语序主语从句要求使用陈述句语序，而非一般疑问句语序。如：Whatsurprisedmemostwasthatthelittlegirlcouldplaytheviolinsowell.使我感到惊讶的是这个小女孩的小提琴拉得太好了。Howhewassuccessfulisstillapuzzle.他是如何成功的仍然是个谜。二.连接词的选用（1）that和what的选用that和what都可引导主语从句。what除起连接作用外，还在名词性从句中充当某些成分，可作从句的主语、宾语或表语。而that在名词性从句中不充当任何成分，无词义，只起连接词作用。如：Whathewantsisabook.他想要的是一本书。Thatlighttravelsinstraightlinesisknowntoall.众所周知，光线沿直线运行。（2）if和whether的选用引导主语从句，不能用if，只能用whether。如：Whetherwewillholdapartyintheopenairtomorrowdependsontheweather.我们明天是否在户外开晚会要看天气而定。（3）其它连接代词和副词的选用根据主语从句的具体意义，正确的选择who,which,when,where,why,how等连接词，这些连接词既有疑问含义，又起连接作用，同时在从句中充当各种成分。如：Whenweshallholdoursportsmeetisnotdecided.我们何时举行运动会还没有决定。Whobroketheglassyesterdayisnotclear.还不清楚昨天谁打破了玻璃。Whichcaryouwillchoosetobuymakesnodifference.你决定买哪一辆车都不会有任何区别。（4）whatever/whoever的功用2whatever,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.）三.it构成的主语从句（1）由连词that引导的主语从句，在大多数情况下会放到句子的后面，而用代词it作形式主语。如：Itiswell-knownthattheearthmovesaroundthesun.众所周知，地球围绕太阳转。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.（主语从句，有that，无逗号）Aswasreported,theUSwasundertheterroristattack.（定语从句，无that，有逗号）上两句意为“据报道，美国遭到恐怖分子的袭击”。（2）常见用it作形式主语的复合句结构aItisafact（agoodidea/apity/ashame/nowonder/goodnews…）that…如：It’sapitythatyoumissedthefilm.你没有看那部电影真是太遗憾了。bItisnecessary（clear/true/strange/important/wonderful/possible/likely…）th需要注意的是，这类主语从句中，谓语动词很多为“（should）＋动词原形”，即要用虚拟语气。如：Itisnecessarythatyou（should）masterthecomputer.你很有必要掌握电脑。ItisimportantthatastudentlearnEnglishwell.学生学好英语很重要。It’sclearthattheybadlyneedhelp.很明显，他们急需援助。Itislikelythatahurricanewillarrivesoon.飓风很可能马上就要到达了。cItisreported（well-known/hoped/thought/expected/said/believed/decided/suggested/ordered…）that…如：3Itissaidthathewaskilledintheearthquake.据说他在地震中丧生了。dItseems（happened/appears/doesn’tmatter/makesnodifference/…）that…如：Itseemsthattheywillwinthegame.看起来他们好像会赢得这场比赛。Itmakesnodifferencewhetherhewillattendthemeetingornot.他是否会参加会议都无关紧。在句中作主语的从句叫主语从句(SubjectiveClause).主语从句是一种重要的名词性从句,在高考试题中频频出现.那么高考对它考查的重点是什么?I.由what等连词引导的从句在主语从句中,what=thething(s)that,它本身在从句中充当某个成分,或是主语,或是宾语,其含义为所做/说/想的.[考题点击]1._______youhavedonemightdoharmtootherpeople.(MET'87)A.ThatB.WhatC.WhetherD.How2._______hesaidatthemeetingastonishedeverybodypresent.(NMET'93)A.WhatB.ThatC.ThefactD.Thematter3._______wecan'tgetseemsbetterthan_______wehave.(NMET'96)A.What;whatB.What;thatC.That;thatD.That;whatII.由that引导的主语从句that在主语从句中不充当具体的句子成分,也无实际词义,只起连接作用,而且当它在句首时,不能省略.[考题点击]4.Itworriedherabit_______herhairwasturninggrey.(MET1992)A.whileB.thatC.ifD.for5._______youdon'tlikehimisnoneofmybusiness.(上海1992)A.WhatB.WhoC.ThatD.WhetherIII.由whether或if引导的主语从句4whether与if皆可引导主语从句,但放在句首常用whether.[考题点击]6._______the2000OlympicGameswillbeheldinBeijingisnotknownyet.(MET'92)A.WheneverB.IfC.WhetherD.That7._______we'llgocampingtomorrowdependsontheweather.(NMET'96)A.IfB.WhetherC.ThatD.WhereIV.由whoever,whatever等引导的主语从句whoever=thepersonwho或anyonewho.who也可以引导主语从句,但只表示谁,如:Whowillwinisnotimportant.anyone与theperson皆不能引导从句.[考题点击]8._______leavestheroomlastoughttoturnoffthelights.(MET'88)A.AnyoneB.ThepersonC.WhoeverD.Who9.Itisgenerallyconsideredunwisetogetachild_______heorshewants.(NMET'97)A.howeverB.whateverC.whicheverD.wheneverV.由it作形式主语引起的主语从句that从句作主语时,常用it作形式主语,而把that引导的主语从句放到句后.在下列情况下,一般使用形式主语it,将主语从句放在句尾.1)谓语是seem,appear,be(im)possible,beapity,beawonder,belikely等.如:Itseemedcertainthatthiswouldwintheprize.Itappearedthathewasright.2)在Itisknown...;Itissaid...;Itishoped...;Itisbelieved...等句型中.如:Itissaidthatourschoolfootballteamwon.3)主语从句也可以用it作形式主语,以wh-连接的句子作真实主语,放到句子后面.如:Itisstillaquestionwhenweshallhaveoursportsmeet.5Itdoesn'tmatterwhatyousay.[考题点击]10.Does_______matterifhecan'tfinishthejobontime?(MET'91)A.thisB.thatC.heD.it11._______isafactthatEnglishisbeingacceptedasaninternationallanguage.(NMET'95)A.ThereB.ThisC.ThatD.It注意:1)有时在Itisnecessary(important,suggested等)+that从句结构中,that从句常用should+动词原形形式来表示虚拟语气,其中should常可省去.[考题点击]12.Itisnecessarythatacollegestudent_______atleastaforeignlanguage.(1993上海)A.mastersB.shouldmasterC.masteredD.willmaster2)在此结构中,要注意句子结构的变化.如NMET2001年的一道高考题:_______isknowntoeverybody,themoontravelsroundtheearthonceeverymonth.A.ItB.AsC.ThatD.What该题很多同学误选了A或C,其原因是没有注意到题中逗号的作用.其实,句中逗号已暗示了该句绝非主语从句,而是as引导的非限制性定语从句,as代表整个主句内容.Key:1-5BAABC6-10CBCBD11-12DB