主语从句讲解及其练习

1、.主语从句一、主语从句的连词分三类（1）从属连词引导的主语从句 （that whether if）that引导的主语从句:引导词that无含义/在句中不做成分/不可以省。That 引导主语从句通常用it 作形式主语。例如：That you will win the medal seems unlikely. That she survived the accident is a miracle.whether 引导的主语从句: whether有含义(是否)/在句中不做成分/不可以省。注意：引导主语从句，不能用if不能在开头，只能用whether。Whether we will hold a p

2、arty in the open air tomorrow depends on the weather. Whether she is coming or not doesnt matter too much.（2） 用连接代词引导的主语从句 在由连接代词who, whose, whom, which, what, whoever, whomever, whichever, whatever引导的名词性从句中，其连接代词在句中起名词性作用，担当一定成分.例如：What you need is more practice. Whatever we do is to serve the peop

3、le.注：whatever / whoever的功用whatever, 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 = anything that; whoever = anyone who。要注意和whatever, whoever引导的让步状语从句的区别。如：Whoever breaks the law should be punished. （主语从句）（ Anyone who breaks the law should be punished. ） Whoever breaks the law, he should be p

4、unished. （让步状语从句）（ No matter who breaks the law, he should be punished. ）（3）用连接副词when, where, why, how引导的名词性从句(其连接副词有含义,在句中作状语。)例如:Where we should leave it is a problem. When they will come hasnt been made pubic.三、it 作形式主语的主语从句有时为了考虑句子平衡，通常在主语从句处使用形式主语it，而将真正的主语从句移至句末。这分四种情况：(1) 对于以连词that引导的主语从句，通常用

5、形式主语it替代主语从句： It is +名词+从句It is a fact that 事实是；It is good news that 是好消息；It is a question that 是个问题；It is common knowledge that 是常识类似的名词还有：a pity；a wonder；a good thing； no wonder； surprise等。It is a mystery to me how it all happened.It is common knowledge that the whale is not a fish.It is no surpri

6、se that Bob should have won the game. It is +形容词+从句It is necessary that 有必要；It is clear that 很清楚；It is likely that 很可能；It is important that 重要的是类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting; aston

7、ishing, etc.It is doubtful whether she will be able to come.It is essential that he should be here by the weekend.It seems obvious that we can not go on like this.It is necessary that you （should）master the computer. 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。 It is +过去分词+从句It is said that 据说；It is

8、 reported that 据报道；It has been proved that 已证明；It must be proved that 必须指出类似的过去分词还有：known; estimated; expected; believed; thought; hoped; noted; discussed; required; decided; suggested; demanded; made clear; found out,etc.例如：It is used to be thought that a new star must be due to a collision between

9、 two stars. It has not been made clear when the new road is to be opened to traffic. It seems不及物动词（happened / appears / doesntt matter / makes no difference / occurred ）that 主语从句不可提前 It makes no difference whether he will attend the meeting or not. It does not matter if I missed my train.It happened

10、 that I saw him yesterday. (2) 对于以连接代词(副词)引导的主语从句，可以使用形式主语代主语从句，也可直接在句首使用主语从句：Whether they would support us was a problem. 他们是否会支持我们还是一个问题。It was a problem whether they would support us.他们是否会支持我们还是一个问题。(3) 对关系代词型what引导的主语从句，通常直接将主语从句放在句首。如：What we need is money. 我们需要的是钱。What I want to know is this.

11、我想知道的就是这一点。有时也可将助用形式主语。如：It is clear enough what he meant. 他是什么意思很清楚。(4) 如果句子是疑问句，则必须用带形式主语it的结构：Is it true that he is the girls father? 他是那女孩的父亲，是真的吗？How is it that you are late again? 你怎么又迟到了？四、连词that的省略问题引导主语从句的连词that 有时可省，有时不能省，其原则是：若that引导的主语从句直接位于句首，则that不能省略；若that引导的主语从句位于句末，而在句首使用了形式主语it，则th

12、at可以省略：That you didnt go to the talk was a pity. 很遗憾你没去听报告。(that不可省)It was a pity (that) you didnt go to the talk. 很遗憾你没去听报告。(that可省)高考题：1、It never occurred to me_C_you could succeed in persuading him to change his mind.(陕西高考)Awhich Bwhat Cthat DIf首先要理解句意.这句话的意思是说,我从来没想到你能够成功地说服他去改变,而不是我从来没想到你能否成功地说

13、服他改变.第二,It never occurred to me是用于对于某个已发生的事实表示惊讶、吃惊的句型,所以这里you could succeed in persuading him to change这个事实只能用that来引导；if是用于引导一个不确定性（uncertainty）的,这里不可以用.2、Its obvious to the students_B_they should get well prepared for their future.(天津卷)Aas Bthat Cwhich DWhether考查名词性从句中的主语从句用法.此处要分析句子结构,看出it为形式主语,代

14、替that they should get well prepared for their future,并且本句意思完整,故选D.3、_B_some people regard as a drawback is seen as a plug by many others.(2010北京)AWhetherBWhat CThat DHow考查名词性从句中的主语从句用法.此处要分析句子结构,看出it为形式主语,代替that they should get well prepared for their future,并且本句意思完整,故选D.4、It is uncertain_A_side eff

15、ect the medicine will bring about，although about two thousand patients have taken it.(2010浙江)Athat Bhow Cwhat DWhetherwhether是“是否”的意思这里应该是选B,what.因为跟后面side effect 连起来,what side effect,一起表示“是什么副作用”整句话的意思是“虽然有两千多个病人服用的这个药,但是对于其带来的具体的什么副作用还是不明确的.”根据意思来选择,只能是Bthat,how,whether都不能表达这个意思.主语从句练习题1._C_ makes

16、 mistakes must correct them.A. What B. That C. Whoever D. Whatever这句话强调的是普遍性，所以用whoever任何人，而不是特指谁2. It worried her a bit _B_ her hair was turning grey.A. while B. that C. if D. for 解析：句意：她的头发渐渐变得花白,使她不安.该题常错选C、D.用if和whether引导该句则句意不通.主语从句较长时,多放在句子后部,用it作形式主语,此时,that也不能省略.3.When and why he came here _

17、A_ yet.A. is not known B. are not known C. has not known D. have not known因为,首先,这是现在完成时,yet 是现在完成时的提示词,但是也可以是一般现在时第二,When and why he came here 这个整个句子做主语,凡是句子做主语的,都是单数,因此是IS第三,这是被动,他何时来为什么来,还尚未为人所知悉如果是现在完成时,是has not been known4. _C_ is no reason for dismissing her.A. Because she was a few minutes lat

18、e B. Owing to a few minutes lateC. The fact that she was a few minutes late D. Being a few minutes late首先,句子不完整,缺的是可以充当主语的名词性的从句.A和B排除,都不是D如果真的要选的话,应该为：Being a few minutes late is no reason for her being dismissed.这个叫主语一致吧C由the fact引导的同位语名词性从句符合要求,主干是：the fact is no reason for dismissing her.5. _D_

19、Tom liked to eat was different from _.A. Thatthat you had expected B. What that you had expectedC. Thatwhat you had expected D. Whatwhat you had expected选A.A.whatwhat作expected的宾语that不能做句子成分意思是“汤姆喜欢吃的东西,与他以前期盼的东西不一样.6._D_ we go swimming every day _ us a lot of good.A. If.do B. That.do C. If.does D. T

20、hat.doesThat指后面每天去游泳的事因为是单3形式所用用does其实去掉中间的we go swimming every day（用来补充that）简单来看,整句就是That dose us a lot of good加上we go swimming every day用来混淆视听罢了7.It _D_ Bob drives badly.A. thinks that B. is thought what C. thought that D. is thought that这种结构都用被动 比如its said that 最常见,只是中间换个词8.Its uncertain _C_ the

21、experiment is worth doing.A. if B. that C. whether D. How应该用whether,对于不确定的事物要用whether,不用that.肯定的时候采用that,比较：I am sure of that he will come.I am not sure whether he will come.9._A_ the boy didnt take medicine made his mother angry.A. That B. What C. How D. WhichWhat 要充当成分,而它后面的句子完整了,主谓宾齐全,所以what改为tha

22、t相当于what made his mother angry is that the boy didnt take medicine10._A_ we cant get seems better than _ we have.A. What, what B. What, that C. That, that D. That, what主要测试主语从句和表语从句。第一空测试主语从句：句子_ we cant get中动词get需要宾语；第二空测试表语从句：句子_ we have中的动词have也需要宾语，结合所给答案可知均选择what最佳。11._C_ you dont like him is n

23、one of my business. A. What B. Who C. That D. Whether用that,句意是 你不喜欢他,这不关我事.That you dont like him is none of my business .句中is是谓语,整个句子是主语从句.从句中you dont like him 表达完整,内容结构都不缺,而主语从句不可省略引导词,于是我们用毫无意义的that来引导该从句.whether 在从句中,有“是否”的意思,此时便不合要求.要用whether,则句子改成：Whether you like him or not is none of my busi

24、ness.你是否喜欢他,这不关我事.12._B_ well go camping tomorrow depends on the weather.A. If B. Whether C. That D. WhereB、C、D三项均可引导主语从句,但是本句含有疑问的意思,因此that排除；根据句意,是否camping和天气关系更为密切,所以where排除；if虽也可表示“是否”,但其不能引导主语从句,也排除.13._D_is going to do the job will be decided by the Party committee.A. That B. Why C. How D. Who

25、这是个主语从句.Who is going to do the job 为主语（从句）,will be decided 为谓语,后面为状语.主语从句一般不用how引导,经常用what that which who why引导14._A_well finish translating the book depends on the time.A. When B. Why C. What D. That我们何时翻译完这本书取决于时间.when引导的主语从句,从句主语,谓语完整,选择连系副词,根据意思选择.15._C_he wont go there is clear to all of us.A. How B. What C. Why D. This为什么他没有来到这里我们所有人都清楚16._B_the house will be built will be