最新英语中的各种从句详解

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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

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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. 过去一直认精品文档．

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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.