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 关系代词 关系副词that、whether；who, what, which , whom, whose, whatever, whoever, whomever, whichever whe 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引导词是否作成分引导词是否可省略连词that陈述句不作成分，也没有实.、八 意在句首时不可省略连词 whether一般疑问句whether在从句中不作 成分，但具有“是否” 的意义不可省略连接

2、畐词 when, 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) who, 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 名词连用不可省略，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 come

3、 or not is still a questi on. shesco ming or not does n't matter too much.it作形式主语，而把主语从句放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 'obvious that -显而易见It '(im)possible(不)可能It 'stra nge that 奇怪的是It 'a fact that 事实是It 'a won der that- 不足为奇 It 'a sh

4、ame that 真是可耻It happened that -碰巧 It turns out that- 结果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 that 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(3) It +

5、不及物动词+that从句It seems that 似乎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 'said that 据说It 'reported that 据报道It' decided that 尚未决定It 'believed that 据认为It 'ann ou need that据宣布It suddenly struck me (occur to me that 我突然想至U (感觉至U) 其他It doesn'tmatter 是无关紧

6、要的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 pityshe has made such a mistake她犯这样的错误是令人遗憾的事。It's strangehe did'come yesterday.他昨天没来是很奇怪的。It is reportedthe 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 saidthere was a terrible pla n

7、e 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

8、可以用if引导.误：If Mary really heard him is really doubtful.正: It was doubtful if Mary really 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

9、式,should有时可以省略。随堂练Doesmatter if he can't fin ish the job on time?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 ntat least a foreig n Ian guage.A. mastersB. should master C. maste

10、redD. will masteris known to everybody, the moon travels round the 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

11、灯。you have done might do harm to other people. 你的行为可能伤害别人。he said at the 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，wha

12、t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，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。连接畐词有 when, where, why, how, however, whenever, whereve等引导主语从句时，它们

13、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 didntcome 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

14、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。(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it作形式主语Is it really true that he has gone abroad? 他真的出国了吗？How surprisi ng it was that he failed in the exam!真令人惊奇，他考试没有及格！(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

15、趣。It 'reported that the highway will be ope ned to traffic n ext week.据报道，高速路下周通车。(3) 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

16、句不可提前。 It doesn'tmatter whether he likes it or n 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

17、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：That he fini shed writi ng the compositi on in such a short timesurprisesus all. 他在如此短的时间内完成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 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

18、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

19、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1. you have done might do harm to other people.A. ThatB. WhatC. WhetherD. How2. _ he said at the meeti ng ast oni shed everybody prese nt.A. WhatB. ThatC. The factD. The matter3. we can'

20、;tget seems better tha nwe have.A. What; whatB. What; thatC. That; thatD. That; what4. It worried her a bither hair was tur ning grey.A. whileB. thatC. ifD. for5. you don't like him is none of my bus in ess.D. WhetherA. WhatB. WhoC. That练习：填入适当的连接词1. It is likelyhe is the winner of this game.很可能

21、他是这场游戏的胜利者。2. she bought so many dicti on aries is not clear.=It is not clearshe 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 pityyou cantatte nd my birthday party.很可惜你不能参加我的生日聚会。5. we w

22、ill 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 ecessarythe 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 possiblehe has stolen the car.很可能他偷了小车。10. has broken the glass is unkn

23、own.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。17. we arri

24、ve 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。19this 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 bither hair was tur ning grey.A. whileB. thatC. ifD. for3. Whe n and why he came hereyet.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 tes lateC. The fact