主語從句和同位語

1、主語從句和同位語主語從句一、主語從句的連詞分三類（1）從屬連詞引導(dǎo)的主語從句 （that whether if）that引導(dǎo)的主語從句:引導(dǎo)詞that無含義/在句中不做成分/不可以省。That 引導(dǎo)主語從句通常用it 作形式主語。例如：That you will win the medal seems unlikely. That she survived the accident is a miracle.whether 引導(dǎo)的主語從句: whether有含義(是否)/在句中不做成分/不可以省略。注意：引導(dǎo)主語從句，不能用if不能在開頭，只能用whether。Whether we will

2、hold a party in the open air tomorrow depends on the weather. Whether she is coming or not doesnt matter too much.（2） 用連接代詞引導(dǎo)的主語從句 在由連接代詞who, whose, whom, which, what, whoever, whomever, whichever, whatever引導(dǎo)的名詞性從句中，其連接代詞在句中起名詞性作用，擔(dān)當(dāng)一定成分.例如：What you need is more practice. Whatever we do is to serve

3、the people.注：whatever / whoever的功用whatever, whoever在主語從句中不含疑問意義。它引導(dǎo)主語從句，并在從句中作主語、賓語、表語等。whatever = anything that; whoever = anyone who。要注意和whatever, whoever引導(dǎo)的讓步狀語從句的區(qū)別。如：Whoever breaks the law should be punished. （主語從句）（ Anyone who breaks the law should be punished. ） Whoever breaks the law, he sho

4、uld be punished. （讓步狀語從句）（ No matter who breaks the law, he should be punished. ）（3）用連接副詞when, where, why, how引導(dǎo)的名詞性從句(其連接副詞有含義,在句中作狀語。)例如:Where we should leave it is a problem. When they will come hasnt been made pubic.三、it 作形式主語的主語從句有時(shí)為了考慮句子平衡，通常在主語從句處使用形式主語it，而將真正的主語從句移至句末。這分四種情況：(1) 對于以連詞that引導(dǎo)的

5、主語從句，通常用形式主語it替代主語從句： It is +名詞+從句It is a fact that 事實(shí)是；It is good news that 是好消息；It is a question that 是個(gè)問題；It is common knowledge that 是常識類似的名詞還有：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 n

6、o surprise that Bob should have won the game. It is +形容詞+從句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 重要的是類似的形容詞還有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interestin

7、g; astonishing, 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. 需要注意的是這類主語從句中，謂語動詞很多為“（should）動詞原形”，即要用虛擬語氣。 It is +過去分詞+從句It is said that

8、據(jù)說；It is reported that 據(jù)報(bào)道；It has been proved that 已證明；It must be proved that 必須指出類似的過去分詞還有：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

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

10、 happened that I saw him yesterday. (2) 對于以連接代詞(副詞)引導(dǎo)的主語從句，可以使用形式主語代主語從句，也可直接在句首使用主語從句：Whether they would support us was a problem. 他們是否會支持我們還是一個(gè)問題。It was a problem whether they would support us.他們是否會支持我們還是一個(gè)問題。(3) 對關(guān)系代詞型what引導(dǎo)的主語從句，通常直接將主語從句放在句首。如：What we need is money. 我們需要的是錢。What I want to know

11、is this. 我想知道的就是這一點(diǎn)。有時(shí)也可將助用形式主語。如：It is clear enough what he meant. 他是什么意思很清楚。(4) 如果句子是疑問句，則必須用帶形式主語it的結(jié)構(gòu)：Is it true that he is the girls father? 他是那女孩的父親，是真的嗎？How is it that you are late again? 你怎么又遲到了？四、連詞that的省略問題引導(dǎo)主語從句的連詞that 有時(shí)可省，有時(shí)不能省，其原則是：若that引導(dǎo)的主語從句直接位于句首，則that不能省略；若that引導(dǎo)的主語從句位于句末，而在句首使用了形

12、式主語it，則that可以省略：That you didnt go to the talk was a pity. 很遺憾你沒去聽報(bào)告。(that不可省)It was a pity (that) you didnt go to the talk. 很遺憾你沒去聽報(bào)告。(that可省) 同位語從句一、理解同位語從句的含義，把握同位語從句的實(shí)質(zhì)在主從復(fù)合句中作同位語的從句稱為同位語從句。同位語從句一般用that, whether，what, which, who, when, where, why, how 等詞引導(dǎo)，常放在fact, news, idea, truth, hope, proble

13、m, information, wish,promise, answer, evidence, report, explanation, suggestion, conclusion等抽象名詞后面，說明該名詞的具體內(nèi)容。換言之，同位語從句和所修飾的名詞在內(nèi)容上為同一關(guān)系，對其內(nèi)容作進(jìn)一步說明。例：The news that they had won the game soon spread over the whole school.他們比賽獲勝的消息很快傳遍了整個(gè)學(xué)校。析：they had won the game說明The news的全部內(nèi)容，因此該句為同位語從句。二、正確運(yùn)用同位語從句的

14、引導(dǎo)詞，準(zhǔn)確把握同位語從句1.如同位語從句意義完整，應(yīng)用that引導(dǎo)同位語從句。（即that 不充當(dāng)任何成分，只起連接作用，不可省略）例：The general gave the order that the soldiers should cross the river at once.將軍下達(dá)了戰(zhàn)士們立即過河的命令。析：the soldiers should cross the river at once是the order的全部內(nèi)容，且意義完整，因此應(yīng)用that引導(dǎo)同位語從句。2.如同位語從句意義不完整，需增加是否的含義，應(yīng)用whether引導(dǎo)同位語從句。（if不能引導(dǎo)同位語從句）例：W

15、ell discuss the problem whether the sports meeting will be held on time.我們將討論運(yùn)動會是否會如期舉行的問題。析：the sports meeting will be held on time意義不完整，應(yīng)加是否的含義才能表達(dá)the problem的全部內(nèi)容，因此應(yīng)用whether引導(dǎo)同位語從句。3.如同位語從句意義不完整，需增加什么時(shí)候、什么地點(diǎn)、什么方式等含義，應(yīng)用when, where, how等詞引導(dǎo)同位語從句。例1：I have no idea when he will be back.析：he will be

16、back意義不完整，應(yīng)加什么時(shí)候的含義才能表達(dá)idea的全部內(nèi)容，因此應(yīng)用when引導(dǎo)同位語從句。例2：I have no impression how he went home, perhaps by bike.析：he went home意義不完整，應(yīng)加如何的含義才能表達(dá)impression的全部內(nèi)容，因此應(yīng)用how引導(dǎo)同位語從句。4.當(dāng)主句的謂語較短，而同位語從句較長時(shí)，同位語從句常后置。如：The thought came to him that maybe the enemy had fled the city.三、把握同位語從句和定語從句的區(qū)別，明確同位語從句和相似從句的界限同位語

17、從句和定語從句相似，都放在某一名詞或代詞后面，但同位語從句不同于定語從句。同位語從句對名詞加以補(bǔ)充說明，是名詞全部內(nèi)容的體現(xiàn)，且名詞和同位語從句的引導(dǎo)詞均不在從句中作成分；定語從句說明先行詞的性質(zhì)與特征，與先行詞是修飾與被修飾的關(guān)系，且名詞和定語從句的引導(dǎo)詞均在從句中作成分。區(qū)分時(shí)可以在先行詞與與從句之間加一個(gè)系動詞be,使之構(gòu)成一個(gè)新句子，如果句子通順且符合邏輯，則為同位語從句，反之，則為定語從句。如：The report that he was going to resign was false.因?yàn)閠he report was that he was going to resign 句意

18、通順，所以，that he was going to resign 是同位語從句。例1：1）Information has been put forward _ more middle school graduates will be admitted into universities.A. while B. that C. when D. as析：答案為B。more middle school graduates will be admitted into universities是Information的內(nèi)容，且Information不在從句中作成分，所以該句為同位語從句。應(yīng)將該句區(qū)別于

19、：2）It is said that more middle school graduates will be admitted into universities，this is the information _ has been put forward.A. what B. that C. when D. as析：答案為B。that has been put forward為information的修飾性定語，且information在從句中作主語，所以該句為定語從句。例2：She heard a terrible noise,_ brought her heart into her m

20、outh.A. it B. which C. this D. that析：答案為B。分析語境含義、句子結(jié)構(gòu)和句子成分可知，該句為非限制性定語從句，先行詞為a terrible noise，且它在從句中作主語。應(yīng)將該句區(qū)別于：I cant stand the terrible noise _ she is crying loudly.A. it B. which C. this D. that析：答案為D。she is crying loudly是the terrible noise的內(nèi)容，且the terrible noise不在從句中作成分，所以該句為同位語從句。同位語從句和定語從句的三點(diǎn)區(qū)

21、別同位語從句和定語從句很相似,但還是有區(qū)別的,區(qū)別主要在以下三方面:1. 從詞類上區(qū)別同位語從句前面的名詞只能是idea,fact,news,hope,belief,suggestion,proposal,word,thought,doubt,truth,possibility,promise,order等有一定內(nèi)涵的名詞?而定語從句的先行詞可以是名詞?代詞?主句的一部分或是整個(gè)主句?如:The possibility that the majority of the labour force will work at home is often discussed. (同位語從句)We ar

22、e not looking into the question whether he is worth trusting.(同位語從句)Word came that he had been abroad. (同位語從句)Our team has won the game, which made us very happy.我們的隊(duì)贏了,這讓我們很高興?(定語從句)The doctor whom you are looking for is in the room.你找的那位醫(yī)生在房間里面?(定語從句)His mother did all she could to help him with h

23、is study.他媽媽盡她的最大努力幫助他的學(xué)習(xí)?(定語從句,代詞all作先行詞?)2. 從性質(zhì)上區(qū)別定語從句是從句對其先行詞的修飾或限制,屬于形容詞性從句的范疇;而同位語從句是從句對前面抽象名詞的進(jìn)一步的說明和解釋,屬于名詞性從句的范疇。如:The news that our team has won the game was true. 我們隊(duì)贏了那場比賽的消息是真的?(同位語從句,補(bǔ)充說明news到底是一個(gè)什么消息)The news that he told me yesterday was true. 昨天他告訴我的那個(gè)消息是真的?(定語從句,news在從句中作told的賓語)I made a promise that if anyone set me free I would make him very rich. 我許諾如果誰讓我自由,我就讓他非常富有?(同位語從句,