主語從句詳細(xì)講解

1、主語從句一、概念：在復(fù)合句中起主語作用的從句叫主語從句。（一） 連接詞 從屬連詞：that、whether； 關(guān)系代詞：who, what, which , whom, whose, whatever, whoever, whomever, whichever； 關(guān)系副詞：when, where, how, why, however, whenever, wherever等；主語從句的引導(dǎo)詞對應(yīng)的簡單句類型引導(dǎo)詞是否作成分引導(dǎo)詞是否可省略連詞that 陳述句不作成分，也沒有實意在句首時不可省略連詞whether一般疑問句whether在從句中不作成分，但具有“是否”的意義不可省略連接

2、副詞when, where, why, how;連接代詞who, whom, what, which, whose特殊疑問句(1)when, where, why, how在從句作狀語；(2)who, whom, what從句中作主語、賓語或表語；(3)which, whose在從句中作定語，后面接名詞連用不可省略，因為它們即作成分，又有意義1. 從屬連詞that，whether引導(dǎo)的主語從句。從屬連詞that，whether在主語從句中的作用只是引導(dǎo)主語從句，在從句中不擔(dān)任成分，不能省略。例： _ they will go is certain._ she will come or

3、 not is still a question. _ shes coming or not doesn't matter too much.2. it作形式主語引導(dǎo)主語從句。如果主語從句太長，為避免句子結(jié)構(gòu)頭重腳輕，我們可用it作形式主語，而把主語從句放在主句謂語部分之后。  用作it作形式主語的結(jié)構(gòu)：(1) It is/was +形容詞+that 從句 Its natural that   很自然      Its obvious that 顯

4、而易見 Its fortunate that 幸運的是         Its (im)possible（不）可能 Its unlikely that 不可能           Its strange that奇怪的是(2)It is/was +名詞+that 從句 Its a pity that   遺憾的是   

5、   Its a fact that 事實是 Its good news that是好消息      Its a wonder that 不足為奇 Its an honour that 非常榮幸     Its a shame that 真是可恥 Its common knowledge that. 是常識(3)It +不及物動詞+that 從句 It seems that 似乎     

6、0;          It happened that碰巧 It appears that看來               It turns out that結(jié)果(4)It is/was +過去分詞+that 從句 Its not known that 不得而知     Its said that 

7、;據(jù)說 Its reported that 據(jù)報道        Its decided that尚未決定 Its believed that 據(jù)認(rèn)為        Its announced that據(jù)宣布 It suddenly struck me (occur to me that 我突然想到（感覺到）(5)其他 It doesnt matter 是無關(guān)緊要的 It makes no differen

8、ce 毫無區(qū)別 It is of little consequence that無關(guān)緊要隨堂練It is a pity _ she has made such a mistake. 她犯這樣的錯誤是令人遺憾的事。It's strange _ he didnt come yesterday. 他昨天沒來是很奇怪的。It is reported _ the number of wild animals in Africa is decreasing.據(jù)報導(dǎo)非洲野生動物的數(shù)量正在減少。It is said _ there was a terr

9、ible plane crash this morning.據(jù)說今天早上有一起可怕的飛機(jī)墜毀事故。注意：1）主語從句在句首時，必須由連接詞引導(dǎo)，不能省略這些連接詞；但是如果用it作形式主語，而把主語從句放在句末時，從屬連詞that在口語中可以省略。誤：They should like each other is natural.正：That they should like each other is natural.正：It is natural that they should like each other.2) 如果主語從句放在句首，不能用if引導(dǎo)，但是如果用it 作形式主語，而把主語

10、從句放在句末時，也可以用if引導(dǎo).誤：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, 主語從句應(yīng)使用虛擬語氣, 謂語動詞用 “should + 動詞原形”的形式或直接用動詞原形。4) 在It + be+suggested/advised/ordered/requested/insisted/required 中, that從句的謂語也應(yīng)該用

11、 “should + 動詞原形”的形式, should有時可以省略。隨堂練Does _ matter if he can't finish the job on time?A. this B. that C. he D. it _ is a fact that English is being accepted as an international language.A. There B. This C. That D. ItIt is necessary that a college student _ at least a foreign language.A. masters

12、B. should master C. mastered D. will master _ is known to everybody, the moon travels round the earth once every month.A. It B. As C. That D. What 3. 由連接代詞引導(dǎo)的主語從句。（1）連接代詞who, what, which, whom, whose, whatever, whoever, whomever, whichever等，引導(dǎo)主語從句時，它們分別在從句中擔(dān)任主語、賓語或定語，不能省略。_ leaves the room last 

13、;ought to turn off the lights. 走得最晚的應(yīng)當(dāng)關(guān)燈。_ you have done might do harm to other people. 你的行為可能傷害別人。_ he said at the meeting astonished everybody present.他在會議上的發(fā)言時所有入會者吃驚。_ made the long distance call is not important. 誰打的長途電話并不重要。（2）what引導(dǎo)主語從句“的東西/事情”時，可用來表示the thi

14、ng(s) which這種意思，引導(dǎo)從句，表示一樣?xùn)|西與一件事情，這種用法的what稱為關(guān)系代詞型what，who，whom，which，what可以和ever構(gòu)成合成詞，和what一樣引導(dǎo)從句，ever起強(qiáng)調(diào)作用。這些關(guān)系詞在句子中充當(dāng)成分，所以不能省略。此類主語從句不能用形式主語it引導(dǎo)。_ (=The thing which I need) is a mobile phone.我所需要的是一部移動電話。_ leaves the office (=Any one who leaves the office) should tell me.無論是誰離開辦公室都應(yīng)

15、該告訴我。4. 關(guān)系副詞引導(dǎo)的主語從句。連接副詞有when, where, why, how, however, whenever, wherever等引導(dǎo)主語從句時，它們在從句中擔(dān)任狀語，不能省略。此類主語從句可以轉(zhuǎn)換為以it作形式主語的句子。_ he didnt come here is not clear to anyone. 他為什么沒來誰也不清楚。_ a telephone works is a question which not everyone can answer. 電話是怎樣工作的，這個問題并不是每個人都能回答。_ she has gone i

16、s not known yet. 她去了哪兒，還不知道。_ they will start has not been decided yet. 他們何時動身還未定下來。_ he did it didn't concern me. 他為什么做這件事與我無關(guān)。（二）位置主語從句不可位于句首的四種情況。(1)含主語從句的復(fù)合句是疑問句、感嘆句時，主語從句不可提前，用引導(dǎo)詞it作形式主語。Is it really true that he has gone abroad? 他真的出國了嗎？How surprising it was that he fai

17、led in the exam! 真令人驚奇，他考試沒有及格！(2)It is said, reported, 結(jié)構(gòu)中的主語從句不可提前。 Its said that the play is very interesting. 據(jù)說戲劇很有趣。 Its reported that the highway will be opened to traffic next week. 據(jù)報道，高速路下周通車。(3)It happens, occurs結(jié)構(gòu)中的主語從句不可提前。 It occurred to her that she had f

18、orgotten to lock the door. 她突然想起忘了鎖門。It happened that I met him in the street. 我恰巧在大街上遇到了他。(4) It doesnt matter how, whether or not結(jié)構(gòu)中的主語從句不可提前。 It doesnt matter whether he likes it or not. 他喜歡與否無關(guān)緊要。 It doesnt matter how he will come. 他怎么來不重要。 （三）主語從句的時態(tài)和單復(fù)數(shù)1. 主語從句的時態(tài)：

19、不受主句的時態(tài)影響和限制。What caused the accident remains unknown. 事故發(fā)生的原因仍未清楚。Who will be our monitor hasnt been decided yet. 誰將擔(dān)任我們的班長還未決定。2. 主語從句大多數(shù)情況下視為三單，但是在what引導(dǎo)的主語從句中，主句謂語動詞的單復(fù)數(shù)要根據(jù)what表示的意義來確定，如：That he finished writing the composition in such a short time surprises us all. 他在如此短的時間內(nèi)完成了作文讓我們很吃驚。What we

20、need is time. 我們需要的是時間。What we need are doctors. 我們需要的是醫(yī)生。What were left behind were five empty bottles. 所留下的東西是五個空瓶子。（四）與其他句型的區(qū)別1. it作形式主語與it引導(dǎo)強(qiáng)調(diào)句的比較。       it作形式主語代替主語從句，主要是為了平衡句子結(jié)構(gòu)（特別是謂語較短時），主語從句的連詞沒有變化。而it引導(dǎo)強(qiáng)調(diào)句則是對某一句子成分的強(qiáng)調(diào)（這一成分可以是詞、詞組或句子），其結(jié)構(gòu)是“It is(was)+ 強(qiáng)調(diào)成分+that”

21、。無論強(qiáng)調(diào)什么成分，都要求用連接詞that(強(qiáng)調(diào)人時可以用who代替)。 It is certain that she will succeed.她會成功是肯定的。（主語從句） It is in New York that I met him.是在紐約我見到了他。（強(qiáng)調(diào)句）2. what 與that 在引導(dǎo)主語從句時的區(qū)別 what 引導(dǎo)主語從句時在句時在從句中充當(dāng)句子成分，如主語賓語表語，而that 則只起連接作用，不作成分。例如： 1) What you said yesterday is right. 2) That she i

22、s still alive is a consolation. 隨堂練1. _ you have done might do harm to other people. A. That B. What C. Whether D. How2. _ he said at the meeting astonished everybody present. A. What B. That C. The fact D. The matter3. _we cant get seems better than _we have. A. What; what B. What; that C. That; th

23、at D. That; what4. It worried her a bit _ her hair was turning grey. A. while B. that C. if D. for 5. _ you don't like him is none of my business. A. What B. Who C. That D. Whether練習(xí)： 填入適當(dāng)?shù)倪B接詞1. It is likely _ he is the winner of this game. 很可能他是這場游戲的勝利者。2. _ she bought so many dictionaries is n

24、ot clear.= It is not clear _ she bought so many dictionaries. 不清楚她為什么買這么多字典。3. _ he was admitted into Beijing University made his teachers and parents happy. 他考上了北大，這讓他的老師和父母很高興。4. Its a pity_ you cant attend my birthday party. 很可惜你不能參加我的生日聚會。5. _ we will build a new high school hasnt been decided.

25、我們是否要建新高中還沒決定呢。6. _ breaks the law should be punished. 不管誰違法都應(yīng)該受到懲罰。7. It is necessary _ the problem (should) be solved at once. 很有必要立刻解決這個問題。8. _ he was born is unknown. 他生于何時還不知道。9 It is possible _ he has stolen the car. 很可能他偷了小車。10. _ has broken the glass is unknown. 誰打破了玻璃現(xiàn)在還不知道。11. _ he wants i

26、s all here. 他所要的東西都在這里。12. _ he worked it out is still a secret. 他是如何把它做出來的還是一個秘密。13. _ they makes in this factory are TV sets. 他們在工廠里所做的東西就是電視機(jī)。14. _ they would support us was a problem. 他們是否會支持我們還是一個問題。15. _ you want is yours. 你要哪個哪個就是你的。16. _ we need is money. 我們需要的是錢。17._ we arrive doesnt matter

27、. 什么時候到?jīng)]有關(guān)系。18. _ it was done was a mystery. 這是怎樣做的是一個謎。19 _ this happened is not clear to anyone. 這件事怎樣發(fā)生的，誰也不清楚。20. _ I spend my summer is no business of yours. 我在哪里過暑假不關(guān)你的事。練習(xí)一1. _ 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. for3. 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