英语中的各种从句详解

从句

一．名词性从句

在句子中起名词作用的各种从句统称为名词性从句。这类从句在句中可担任主语、表语、宾语和同位语，名词从句可以分为主语从句、表语从句、宾语从句和同位语从句。 1.主语从句

在句子中担当主语的是一个句子，这个从句就叫作主语从句。主语从句可以由下列连词、连接代词和连接副词引导，且不能省略。 连词：that, whether

连接代词：what, whatever, who, whoever 等 连接副词：when, where, how, why (1)由连词that, whether引导的主语从句

连词that, whether在从句中的作用只是引导主语从句，它在从句中不担任成分，不能省略，且由that, whether引导的主语从句，多用it多形式主语

e.g That the earth is round is true.=It is true that the earth is round.地球是圆的，是一个事实。 Whether he’ll come or not hasn’t been decided.= It hasn’t been decided whether he’ll come or not.

(2)由连接代词或连接副词引导的主语从句

连接代词who, which和连接副词when, where, how, why都可以引导主语从句，它们分别在从句中担任主语、宾语和状语，不能省略，翻译时，不能把它们译为疑问句，由它们引导的主语从句，也可以用形式主语it引导

e.g Who let out the news remained unknown. =It remained unknown who let out the news.谁泄漏了那个消息仍旧无人知道。

When we’ll start is not clear. =It is not clear when we’ll start.我们何时出发还不清楚。

(3)以关系代词what, whatever, whoever, whomever, whichever引导的主语从句不能用形式主语it引导，它们在句子中担任成分，不能省略，语序为陈述语序。 e.g What he said at the meeting is important.他在会上所说的事情是重要的。 Whoever leaves the office should tell me.无论是谁离开办公室都应该告诉我。

(4)用it作形式主语的主语从句结构 a. 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。 例如：It is a mystery to me how it all happened. 这一切是怎么发生的是个谜。

It is common knowledge that the whale is not a fish. 鲸鱼不是鱼，这是常识。

It is no surprise that Bob should have won the game. 鲍勃会赢得这场比赛，这不足为奇。 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; astonishing, etc. 例如：It is obvious that conductors and insulators are both important in industry. 很明显导体和绝缘体在工业中都很重要。 It is doubtful whether she will be able to come. 她是否能来令人怀疑。

It was really astonishing that he refused to talk to you . 他拒绝和你说话真是令人惊讶。

It is essential that he should be here by the weekend . 周末之前，他应该到这里是必要的。 It seems obvious that we can not go on like this. 很明显我们不能这样下去了。 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; noted; discussed; required; decided; suggested; demanded; made clear; found out,etc. 例如：It is thought that he is the best player. 大家都认为他是最好的选手。

It is estimated that the vase is 2000 years old. 据估计这个花瓶有2000年的历史。

It is used to be thought that a new star must be due to a collision between two stars. 过去一直认

为新星是由于两颗星星之间碰撞产生的。

It has not been made clear when the new road is to be opened to traffic. 还没弄清楚这条路将开始通车。 d. It +不及物动词+从句 It seems that … 好像是…… It happened that… 碰巧…… It follows that … 由此可见…… It has turned out that … 结果是……

类似的不及物动词还有：seem, appear, occur, follow, happen, turn out, etc. 例如：It turned out that nobody remembered the address. 结果是无人记得那个地址。

It now appears that they are in urgent need of help. 看起来他们急需帮助。

It does not matter if I missed my train, because there is another later. 没有赶上这趟火车没有关系，稍晚还有一趟。 It happened that I saw him yesterday. 碰巧我昨天看见他了。

当“及物动词 + 宾语”较短时，也可用这种结构。

例如：It shocked me that Peter did not tell anybody where he was. 让我吃惊的是彼得没有告诉任何人他在哪里。 It does not interest me whether you go or not. 我对你去不去不感兴趣。 e. It +某些固定结构+ 主语从句。 It doesn’t matter??是无关紧要的?? It makes no difference??毫无区别??

It doesn’t make too much difference that?? ??关系不大 It doesn’t need to be bothered that??不必担忧?? 例如：

It does not make any difference whether it rains or not . 下不下雨没什么分别。

It does not make the least difference to me what you do. 对我来说你做什么都无关紧要。

2. 宾语从句

用作宾语的从句叫宾语从句。 1.引导宾语从句的关联词有三类： (1) 从属连词that。如：

He told us that he felt ill. 他对我们说他感到不舒服。 I know he has returned. 我知道他已经回来了。

注： that在引导宾语从句时也并不是任何情况下都可以省略。在以下情况下，that不能省略。 1. Everybody could see what happened and that Tom was frightened. 大家都会看出所发生的事情并知道Tom非常害怕。

and连接两个宾语从句，that宾语从句放在and的后面时，that不能省略。

2. I know nothing about him except that he is from the south. 对他我一无所知，只知道他是南方人。

that引导的宾语从句作介词宾语时，that不能省略。

3. That he ever said such a thing I simply don’t believe. 我简直不相信他曾说过这样的话。 that从句位于句首时，that不可省略。

4. We decided, in view of his special circumstances, that we would admit him for a probationary period. 鉴于他的特殊情况，我们决定应允他一段试用期。 主句谓语动词与that从句之间有插入语，that不可省略。 (2)从属连词if/whether。如：

I doubt whether he will succeed. 我怀疑他是否会成功。 I don’t know if you can help me. 我不知道你能否帮助我。

(3)连接代词who, whom, whose, what, which, whoever, whatever, whichever 连接副词 where, when, how, why。

e.g Who or what he was, Martin never learned. 他是什么人？他是干什么的？马丁根本不知道。

I wonder what he’s writing to me about. 我不知道他要给我写信说什么事。 I’ll tell you why I asked you to come. 我会告诉你我为什么要你来。

2. 介词宾语从句

宾语从句也可用作介词的宾语。如：

He was deeply displeased by what had occurred that day.他对那天发生的事感到很不快。 I walked over to where she sat. 我走向她坐的地方。 有时介词可以省略。如：

I don’t care (for) who marries him. 我不管谁跟他结婚。 Be careful (as to) how you do that. 你要注意做这件事的方式.

注意：连词that引导的名词性从句很少作介词的宾语，只用在except, but, in后。其他一些

介词的宾语从句如果由连词that引导，则需用it先行一步，作形式宾语。 如：He is a good student except that he is careless.他是一个好学生，只是有点粗心。 You may rely on it that I shall help you. 你可以指望我会帮助你的。

3. 动词＋it＋that结构

如果宾语从句后还有宾语补足语，则用it作形式宾语，而将宾语从句后置。如：

We thought it strange that Xiao Wang did not come yesterday.我们认为小王昨天没来是奇怪的。

He has made it clear that he will not give in.他已表明他不会屈服。

4. 某些形容词或过去分词后常接宾语从句，这类形容词或过去分词有sure, glad, certain, pleased, happy, afraid, surprised, satisfied等，连词that可省略。如： I am not sure what I ought to do.我不能确定我该做什么。

I’m afraid you don’t understand what I said.恐怕你没领会我说的意思。 I’m surprised that I didn’t see all that before.我好奇怪，我以前没看到过。

5. 连词whether (?or not)或if引导的宾语从句

if和whether引导的宾语从句可以互换使用，但whether常和or not连用，if一般不与or not连用。如：

I wonder whether it is true or not. 我不知它是真是假。

用if引导宾语从句如果会引起歧义，应避免使用if而用whether。试比较： Please let me know if you want to go. Please let me know whether you want to go.

(if从句可理解为宾语从句，意为“请告诉我你是否想去”；此句又可理解为条件状语从句意为“如果你想去的话，请告诉我一声”。)

6. 宾语从句的否定转移。在think, believe, suppose, expect等动词后的宾语从句，有时谓语尽管是否定意思，却不用否定形式，而将think等动词变为否定形式。如： I don’t think you are right. 我认为你错了。

I don’t believe they have finished their work yet. 我相信他们还未完成他们的工作。

3. 表语从句

表语从句放在连系动词之后，充当复合句中的表语, 一般结构是“主语＋连系动词＋表语从句”。可接表语从句的连系动词有be，look，seem，sound，appear等。 如：China is no longer what she used to be. 今日的中国不再是过去的中国了。

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