名词性从句---主语从句
主语从句subject clauses)
1、概述; 在复合句中起主语作用的从句叫主语从句。
引导主语从句的词有从属连词、连接代词、连接副词等。引导主语从句的关联词有从属连词that、whether,
连接代词: who, what, which , whom, whose, whatever, who (m) ever, whichever;连接副词: when, where, how, why, however, whenever, wherever等。That you don't like him is none of my business.你不喜欢他不管我的事。What he said is true.他说的是真的。
2、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，它们在从句中不担任成分，不能省略。
Whether she will come or not is still a question.她是否会来仍是一个问题。
That they will go is certain.他们去是肯定的。
Whether she's coming or not doesn't matter too much.她来不来没有多大关系。
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3、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it作形式主语,而把主语从句放在主句谓语部分之后。That引导的主语从句可用it代替，that 不可省略。
用作it作形式主语的结构:
(1) It is/was +形容词+that从句
It's natural that... 很自然.... It's obvious that...显而易见......
It's fortunate that幸透的是 It's impossible that. (不)可能 It's unlikely that..不可能
It's strange that...奇怪的是 (2 It is/was +名司+that从句
It's a pity that.-遺 憾的是 It's a fact that..事実是
It's good news that..是好消息-- It's a wonder that.不足カ奇It's an honor that..非常荣幸的是--- It's a shame that.. .真是可耻It's common knowledge that .是常沢..
(3) It +不及物动词+that从句
It seems that.--似乎 It happened that..磋巧It appears that..看来 It turns out
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that..結果
(4) It is/was +过去分词+that从句
It's not known that.. --不得而知 It's said that..据説It's reported that.-据狠道 It's decided that..尚未决定
It's believed that..据相信 It's announced that..据宣布-It suddenly struck me (occur to me that.我突然想到(感觉到) -(5)其他
It doesn't matter是无美緊要的
It makes no difference .. ,亳无区別-It is of little consequence that..无美緊要例句:
It is a pity that she has made such a mistake.地犯込祥的錯俣是令人遺憾的事。
It's strange that he didn't come yesterday.他昨天没来是很奇怪的。
It is reported that the number of wild animals in Africa is decreasing.据扱尋非洲野生劫物的数量正在減少。
It is said that there was a terrible plane crash this morning.据説今天早上有一起可怕的K机坐毀事故。
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It seems that Tom has got a cold. 汤姆好像生病了。
4、由连接代词引导的主语从句。
(1)关系代词who, what, which, whom, whose, whatever, whoever, whomever,whichever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(whose)，不能省略。
Whoever leaves the room last ought to turn off the lights.走得最晚的应当关灯。
What you have done might do harm to other people.你的行为可能伤害别人。
What he said at the meeting astonished everybody present.他在会议上的发言使所有入会者吃惊。
Who made the long distance call is not important.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- ~件事情，这种用法的what称为关系代词型what, who, whom, which, what 可以和ever构成合成词，和what -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。
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What I need (=The thing which I need) is a mobile phone.我所需要的是-部移动电话。
Whoever leaves the office (= Anyone who leaves the office)should tell me.无论是谁离开办公室都应该告诉我。5、连接副词引导的主语从句。
连接副词有when, where, why, how, however, whenever, wherever等引导主语从句时，它们在从句中担任状语，不能省略。Why he didn't come here is not clear to anyone.他为什么没来谁也不清楚。
How a telephone works is a question which not everyone can answer.电话是怎样工作的，这个问题并不是每个人都能回答,
Where she has gone is not known yet.她去了哪儿，还不知道。
When they will start has not been decided yet.他们何时动身还未定下来。Why he did it didn't concern me.他为什么做这件事与我无关。
6、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 surprising 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。
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It's said that the play is very interesting据说戏剧很有趣。
It's reported that the highway will be opened to traffic next week据报道，高速路下周通车。
(3) It happens, 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 happened that I met him in the street我恰巧在大街上遇到了他。
(4) It doesn't matter how, whether or not..结构中的主语从句不可提前。It doesn't matter whether he likes it or not他喜欢与否无关紧要。It doesn't matter how he will come.他怎么来不重要。
7、it 作形式主语与it引导强调句的比较。
it作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+that\"。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 certain 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)
课堂练习：
1. I have always been honest and straightforward, and it doesn't matter _that I'm
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talking to.
A. who is it B. who it is c. it is who D. it is whom
2. It is pretty well understood_ controls the flow of carbon dioxide in and out the atmosphere today.
A. that B. when c. what D. how
3.___ made the school proud was_ more than 90% of the students had been admitted to key universities.
A. What; because B. What; that c. That ; what D. That ; because
4. ____ we will go camping tomorrow depends on the weather.
A. If B. Whether c. That D. Where
5._ that they can pass the written exam this time.
A. That is hoped B. It is hoped c. It hopes D. That hopes
6.___ leaves the room last ought to turn off the lights.
A. Anyone B. The person c. Whoever D. Who .
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7.___ is a fact that English is being accepted as an international language.
A. There B. This c. That D. It
8._ in the newspaper that the price of food will go up.
A. It says . B.It is said. C. It has said D. He is said
9, It worried her a bit. _her hair was turning grey.
A. while B. that C. if D. for
10. There is no doubt______.
A. that Mr. Hansen is in good health B. whether is Mr. Hansen healthy. C if Mr. Hansen's health was returning D. whether Mr. Hansen in health
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