主语从句详解.docx

1、主语从句详解 主语从句详解一、概述在句子中起名词作用的各种从句统称为名词性从句.根据它们在句中的语法作用, 这类从句又可分为主语从句、同位语从句、表语从句和宾语从句.二、主语从句主要有四类（1） 由连词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.例如：That you will win the medal seems unlikely.That you are so indifferent bothers me.That she survived the accident is a miracle.（2） 用连词 whether 引导的主语从句: whether有含

2、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, 只能用whether.例如：Whether we will hold a party in the open air tomorrow depends on the weather. Whether she is coming or not doesnt matter too much.（3） 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,

3、担当一定成分.例如：What you need is more practice. What I want to know is this. Whatever we do is to serve the people.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.Whoever breaks the law should be

4、 punished. （主语从句）（Anyone who breaks the law should be punished. ）Whoever breaks the law, he should be punished. （让步状语从句）（No matter who breaks the law, he should be punished. ）（4）用连接副词when, where, why, how引导名词性从句(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

5、 made pubic.三、注意点: it构成的主语从句（1）由连词that引导的主语从句, 在多数情况下放到句子的后面, 而用代词it作形式主语.例如：That light travels in straight lines is known to all.=It is known to all that light travels in straight lines.When the plane is to take off has not been announced .= It has not been announced when the plane is to take off.(

6、但当what引导的主语从句表示“的东西”时, 一般不用it作形式主语.)错:It is a book what he wants.对:What he wants is a book. 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：It was reported that the US was under the terrorist attack. As was reported, the US was under the terrorist attack. （2）常见用it作形式主语的复合句结构A. It is +名词+从句It is a f

7、act 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.例如：It is a mystery to me how it all happened.It is common knowledge that the whale is not a fish.It is no surprise that Bob should have won the gam

8、e.Its a pity that you missed the film. B. 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; asto

9、nishing, etc.例如：It is doubtful whether she will be able to come.It was really astonishing that he refused to talk to you.It is essential that he should be here by the weekend.It seems obvious that we cannot go on like this.It is necessary that you （should）master the computer. It is important that a

10、student learn English well. It is likely that a hurricane will arrive soon.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.C. It is +过去分词+从句It is said that 据说It is 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; n

11、oted; discussed; required; decided; suggested; demanded; made clear; found out,etc.例如：It is thought that he is the best player.It is estimated that the vase is 2000 years old.It is used to be thought that a new star must be due to a collision between two stars. It has not been made clear when the ne

12、w road is to be opened to traffic.It is said that he was killed in the earthquake. D. It seems（happened / appears / doesnt matter / makes no difference / occurred ）that It seems that they will win the game. It makes no difference whether he will attend the meeting or not. It does not matter if I mis

13、sed my train.It happened that I saw him yesterday.主从练习1. _asmuchasone-fifthofalltimberharvestedisnotused.A.Theestimate B.TheestimatedC.Theyareestimated D.Itisestimatedthat2._somemammals cametoliveintheseaisnotknown.A.WhichB.SinceC.AlthoughD.How3._wehaveachievedisattributedtotheguidanceofourparents.A

14、.WhoeverB.WhateverC.HoweverD.That4._wealthydoesnotnecessarilymeanthatamanisgreedy.A.ForthereasonthatheisB.JustbecauseheisC.ThereasonofbeingD.Thatheis5.Although_happenedinthisdevelopedcountrysoundslikesciencefiction, itcouldoccur elsewhereintheworld.A.whichB.whatC.howD.it6._shehadforgottentotakeherno

15、tebook.A.ThatoccurredtoherB.SheoccurredthatC.ToherthatoccurredD.Itoccurredtoherthat7.Iamsurethat_shesaidiswrong.A.whichB.allC.thisD.what8.Welostourwayintheforest,and_mademattersworsewasthatitwasgettingdark.A.thatB.whichC.itD.What9._ornotisstilluncertain.A.HescomingB.Ifheiscoming C.ThatcomingD.Whethe

16、rhescoming10.Its_hellbeabletocome.A.doubtwhetherB.doubtfulC.doubtitD.doubtfulwhether11._heisatworkintheheartofthebigcityorathomeinthequiet suburb,Dickslifeistiedtomachines.A.WhetherB.TillC.IfD.Unless12._hesawbothsurprisedandfrightenedhim.A.ThatB.WhenC.WhatD.Which13._is warmsunshine.A.Whatdoweallneed

17、.B.WhatallweneedC.Whatweneed D.Whatweallneed14._isapitythatheshouldfeelsoupset.A.WhatB.ThatC.HeD.It15._aspoonfulofsoilcantellussomuchaboutthestructureandearlyhistoryofthemoon.A.RemarkableB.QuiteremarkablyC.ItisremarkablethatD.Itisremarkablefactthat16._younominatewillbeelected.A.WhoB.WhomC.WhomeverD.

18、Thats17._bookyouborrowmustbereturnedwithinaweek.A.WhatB.WhichC.WhicheverD.Thats18._ofusgetshomefirststartscooking.A.WhoB.WhichC.WhicheverD.Anyone1._ makes mistakes must correct them.A. What B. That C. Whoever D. Whatever2. It worried her a bit _ her hair was turning grey.A. while B. that C. if D. fo

19、r 3.When and why he came here _ yet.A. is not known B. are not known C. has not known D. have not known4. _ is no reason for dismissing her.A. Because she was a few minutes late B. Owing to a few minutes lateC. The fact that she was a few minutes late D. Being a few minutes late5. _ Tom liked to eat

20、 was different from _.A. Thatthat you had expected B. What that you had expectedC. Thatwhat you had expected D. Whatwhat you had expected6._ we go swimming every day _ us a lot of good.A. If.do B. That.do C. If.does D. That.does7.It _ Bob drives badly.A. thinks that B. is thought what C. thought tha

21、t D. is thought that8.Its uncertain _ the experiment is worth doing.A. if B. that C. whether D. how9._ the boy didnt take medicine made his mother angry.A. That B. What C. How D. Which10._ we cant get seems better than _ we have.A. What, what B. What, that C. That, that D. That, what11._ you dont li

22、ke him is none of my business. A. What B. Who C. That D. Whether12._ well go camping tomorrow depends on the weather.A. If B. Whether C. That D. Where13._is going to do the job will be decided by the Party committee.A. That B. Why C. How D. Who14._well finish translating the book depends on the time

23、.A. When B. Why C. What D. That15._he wont go there is clear to all of us.A. How B. What C. Why D. This16._the house will be built will be discussed at tomorrows meeting.A. If B. Where C. That D. What17._you come or not is up to you.A. What B. If C. Why D. Whether18._makes mistakes must correct them

24、.A. Who B. Anyone C. Whoever D. Anybody19._team will win the match is a matter of public concern.A. Which B. That C. If D. How20. Who is this factory _ some foreign friends visited last Friday?A. that B. where C. which D. the one21.Is this factory you visited the other day?A. that B. where C. in whi

25、ch D. the one22._leaves the room last ought to turn off the lights.A. Anyone B. The person C. Whoever D.Who 表语从句1、概述用作表语的从句叫作表语从句, 它位于主句中的连系动词之后.引导表语从句的词有从属连词that、whether、as though(if)；关系代词who, what, which, whom, whose, whatever, whoever, whomever, whichever等；关系副词when, where, why, how, however, when

26、ever, wherever等.可以接表语从句的连系动词由be, look, remain, seem等.That引导表语从句时, 在口语中, 间或可以省略.The trouble is that we are short of money.困难是我们资金短缺.That is why stone walls are used instead of fences around New England fields.这就是为什么在新英格兰用石头墙而不用栅栏的原因.At that time, it seemed as if I couldnt think of the right word anyh

27、ow.当时,我似乎怎么也想不出一个恰当的字眼来.2、由从属连词that, whether引导的表语从句.that在引导表语从句时无词义, 而whether有词义, 意为、“是否”.这时主句的主语常常是些抽象名词, 如question(问题), trouble(麻烦), problem(问题), result(结果), chance(可能性), suggestion(建议), idea(想法), reason(理由)等.表语从句对主句主语进行说明、解释, 使主语的内容具体化. The trouble is (that) she has lost his money. 麻烦的事是他丢了钱.The

28、question is whether we need more ice cream.问题是我们是否还需要一些冰淇淋.The problem was that it was too valuable for everyday use.问题是它作为日常之用太贵重了.What she couldnt understand was that fewer and fewer students showed interest in her lessons. 我们不能理解越来越少的学生对他的课不感兴趣.3、由关系代词引导的表语从句.关系代词who, what, which, whom, whose, whatever, whoever, whomever, whichever等引导表语从句,