主语从句详细讲解

1、主语从句、概念：在复合句中起主语作用的从句叫主语从句。(一)连接词从属连词that、whether ;关系代词who, what, which , whom, whose, whatever, whoever, whomever, whichever whe关系副词n, where, how, why, however, whe never, whereve等 ；主语从句的引导词对应的简单句类型毋否加感女士引导词是否可省略连词that陈述句不作成才正也汉有 头 .、/ V 后、在旬首时不可省略连词 whether一般疑问句whether在从句中不作成分，但具有“是否”义不可省略 的意连接词 w

2、hen, where, why, how;连接代词 who, whom, what, which, whose特殊疑问句(1) whe n, where, why, how在从句作状语；(2) w ho, whom, what从句中作主语、宾语或表 语；(3)which, whose 在从 句 中作定语，后面接名词连41不可省略，因为它们即作 成分，又有意义1.从属连词that ) whether 引导的主语从句。从属连词that , whether在主语从句中的作用只是引导主语从句，在从句中不担任成分，不能 省略。例:they will go is certa in.she will com

3、e or not is still a questi on.shesco ming or not does n't mattertoo much.2. it作形式主语引导主语从句。如果主语从句太长，为避免句子结it作形式主语，而把主语从句放构头重脚轻，我们可用在主句谓语部分之后。用作it作形式主语的结构:It is/was + 形容词+that 从句It'natural that 很 自然 It 'fortunate that 幸运的是It 'unlikely that 不可能(2) lt is/was + 名词 +that 从句It 'a pity t

4、hat遗憾的是 It 'good n ews that 是好消息 It 'an honour that非常荣幸It 'com mon kno wledge that-. 是常识It +不及物动词+that从句It seems that 似乎It'obviousthat -显而易见一It'(im)pIt happened that -碰巧It turns out that-?结It appears that 看来(4)lt is/was + 过去分词 +that 从句It 'not known that 不得而知It 'reported t

5、hat据报道It 'believed that据认为It suddenly struck me (occur to me that其他It doesn'tmatter 是无关紧要的It 'said that 据说It' decided that ? 尚未决定It 'ann ou need that据宣布 我突然想至U (感觉至U) It makes no differenee 毫无区另 SIt is of little con seque nee that 无关紧要 随堂练 It is a pity s_he has made such a mistak

6、e 她犯这样的错误是令人遗憾的事。It's strange he did 'come yesterday. 他昨天没来是很奇怪的。It is reported the nu mber of wild ani mals in Africa is decreas ing.据报导非洲野生动物的数量正在减少。It is said there was a terrible pla ne crash this morni ng.据说今天早上有一起可怕的飞机坠毁事故。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 作形式主语, 而把主语从句放在句末时，从属连词

7、that 在口语中可以省略。误： They should like each other is natural.正： That they should like each other is n atural.正 : It is natural that they should like each other.2 ) 如果主语从句放在句首，不能用 if 引导，但是如果用 it 作形式主语，而把主语从句放在 句末时，也可 以用 if 引导 .误： If Mary really heard him is really doubtful.正 : It was doubtful if Mary real

8、ly heard him.3 ) 用于 It is important / natural / necessary / impossible that.句型中 ， 主语从句应使用虚拟语气谓语动词用 should + 动词原形”的形式或直接用动词原形。4 ) 在 It + be+suggested/advised/ordered/requested/insisted/require中 ， that 从句的谓语也应该用“ should + 动词原形”的形式,should 有时可以省略。 随堂练 Does m atter if he can't fin ish the job on time

9、?A. thisB. thatC. heD. itis a fact that En glish is being accepted as an intern ati on al la nguage.A. ThereB. ThisC. ThatD. ItIt is n ecessary that a college stude nt at least a foreig n Ian guage.A. mastersB. should master C. masteredD. will masteris known to everybody, the moon travels round the

10、earth once every month.A. ItB. AsC. ThatD. What3.由连接代词引导的主语从句。(1 )连接代词who, what, which, whom, whose, whatever, whoever, whomever, whicheve等，引 导主语从句时，它们分别在从句中担任主语、宾语或定语，不能省略。leaves the room last ought to turn off the lights.走得最晚的应当关灯。you have done might do harm to other people.你的行为可能伤害别人。he said at t

11、he meeti ng ast oni shed everybody prese nt.他在会议上的发言时所有入会者吃惊。made the long dista nee call is not importa nt.谁打的长途电话并不重要。(2) what 引导主语从句“ 的 东西 /事情”时，可用来表示the thing(s) which 这种意思，引导从句，表示一样东西与一件事情，这种用法的 what 称为关系代词型what ， who , whom ，which ， what 可以和 ever 构成合成词，和 what 一样引导从句， ever 起强调作用。这些关系词 在句子中充当成分，

12、所以不能省略。此类主语从句不能用形式主语it 引导。二( The thing which I n eed) is a mobile pho ne.我所需要的是一部移动电话。leaves the office (=A ny one who leaves the office) should tell me.无论是谁离开办公室都应该告诉我。4. 关系副词引导的主语从句。连接词有 when, where, why, how, however, whenever, whereve等弓I导主语从句时，它们在从句中担任状语，不能省略。此类主语从句可以转换为以 it 作形式主语的句子。he didntcom

13、e here is not clear to anyone.他为什么没来谁也不清楚。a telepho ne works is a questi on which not every one can an swer.电话是怎样工作的，这个问题并不是每个人都能回答。she has gone is not known yet. 她去了哪儿，还不知道。they will start has not bee n decided yet. 他们何时动身还未定下来。he did it did n't c on cern me.他为什么做这件事与我无关。(二 ) 位置 主语从句不可位于句首的四种情况

14、。他真的出国了吗？真令人惊奇，他考试没有及格！it 作形式主语(1) 含主语从句的复合句是疑问句、感叹句时，主语从句不可提前，用引导词Is it really true that he has gone abroad?How surprisi ng it was that he failed in the exam!(2)It is said, reported,结构中的主语从句不可提前。It 'said that the play is very in teresti ng. 据说戏居 U 很有趣。It 'reported that the highway will be o

15、pe ned to traffic n ext week.据报道，高速路下周通车。It happe ns, occurs结构中的主语从句不可提前。It occurred to her that she had forgotten to lock the door.她突然想起忘了锁门。It happe ned that I met him in the street. 我恰巧在大街上遇到了他。(4) It does n'tmatter how, whether or n ot结构中的主语从句不可提前。It doesn'tmatter whether helikes it or n

16、 ot.他喜欢与否无关紧要。It does n'tmatter how he will come.他怎么来不重要。（三 ）主语从句的时态和单复数1. 主语从句的时态：不受主句的时态影响和限制。What caused the accide nt remai ns unknown事故发生的原因仍未清楚。Who will be our mo nitor has n'tbeen decidedyet. 谁将担任我们的班长还未决定。2. 主语从句大多数情况下视为三单， 但是在 what 引导的主语从句中， 主句谓语动词的单复 数要根据 what 表示的意义来确定，如：10surprise

17、s us all. 他在如此短的时间内完成1. you have done might do harm to other people.A. ThatB. WhatC. Whether2. _ he said at the meeti ng ast oni shed everybody prese nt.A. WhatB. ThatC. The fact3. _ we can'tget seems better tha n we have.A. What; whatB. What; thatC. That; thatD. That; what4. It worried her a bi

18、t her hair was tur ning grey.A. whileB. thatC. if5. you don't like him is none of my bus in ess.A. WhatB. WhoC. ThatD. HowD. The matterD. forD. WhetherThat he fini shed writi ng the compositi on in such a short time了作文让我们很吃惊。What we need is time. 我们需要的是时间。What we n eed are doctors. 我们需要的是医生。What

19、 were left beh ind were five empty bottles.所留下的东西是五个空瓶子。（四）与其他句型的区别1. it 作形式主语与 it 引导强调句的比较。it 作形式主语代替主语从句，主要是为了平衡句子结构（特别是谓语较短时） ，主语从句的连词没有变化。而it 引导强调句则是对某一句子成分的强调（这一成分可以是词、词组或 句子），其结构是“ It is （was ） +强调成分 +thaf' 。无论强调什么成分，都要求用连接词 that （强 调人时可以用 who 代替 ） 。It is certai n that she will succeed 她会成

20、功是肯定的。（主语从句） It is in New York that I met him. 是 在纽约我见到了他。（强调句）2. what 与 that 在引导主语从句时的区别what 弓 I 导主语从句时在句时在从句中充当句子成分，如主语?宾语 ?表语，而 that 则只起连接作用，不作成分。例如：1 ） What you said yesterday is right.2 ） That she is still alive is a con solati on. 随堂练 练习：填入适当的连接词1. It is likely he is the winner of this game.很可

21、能他是这场游戏的胜利者。2. she bought so many dicti on aries is not clear.=It is not clear she bought so many dict ion aries.不清楚她为什么买这么多字典。3. he was admitted into Beiji ng Un iversity made his teachers and pare nts happy.他考上了北大，这让他的老师和父母很高兴。4. It 'a pity you cantatte nd my birthday party.很可惜你不能参加我的生日聚会。5. w

22、e will build a new high school hasntbee n decided.我们是否要建新高中还没决定呢。6. breaks the law should be punished. 不管谁违法都应该受到惩罚。7. It is n ecessary the problem (should) be solved at on ce.很有必要立刻解决这个问题。8. he was born is unknown. 他生于何时还不知道。9. It is possible he has stolen the car. 很可能他偷了小车。10. has broken the glass

23、 is unknown.谁打破了玻璃现在还不知道。11. he wants is all here. 他所要的东西都在这里。12. he worked it out is still a secret.他是如何把它做出来的还是一个秘密。13. they makes in this factory are TV sets.他们在工厂里所做的东西就是电视机。14. they would support us was a problem.他们是否会支持我们还是一个问题。15. you want is yours. 你要哪个哪个就是你的。16. we n eed is mo ney. 我们需要的是钱。

24、17. we arrive does 'matter.什么时候到没有关系。18. it was done was a mystery. 这是怎样做的是一个谜。19. this happe ned is not clear to anyone.这件事怎样发生的，谁也不清楚。20. I spe nd my summer is no bus in ess of yours.我在哪里过暑假不关你的事。练习一1. makes mistakes must correct them.A. WhatB. ThatC. WhoeverD. Whatever2. It worried her a bit her hair was tur ning grey.A. whileB. thatC. ifD. for3. Whe n and why he came here yet.A. is not knownB. are not knownC. has not knownD. have not known4. is no reas on for dismiss ing her.A. Because she was a few minu tes lateB. Owi ng to a few minu te