英语三大从句

复合句

【语法要点】

复合句是由一个主句加一个或几个从句所构成的句子。从句只用作句子的一个成分，不能独立。根据从句在句子中的作用，可分为名词性从句、定语从句和状语从句三类。

（一）名词性从句

名词性从句包括主语从句、表语从句、宾语从句、同位语从句。其关联词有连接词that、if、whether；疑问代词who、what、which和疑问副词when、where、how、why等。

1.名词性从句句法结构：

从

属

连

词that whether

主

语

从

句That he will come is certain.（that不可省）

Whether she is coming or not doesn’t matter too much.

（不能用if）

宾

语

从

句I think（that）he will be all right in a few days.

I went in and asked if（=whether）they had a cheap suit.

I wonder whether（不能用if）it is true or not.

表

语

从

句

The fact is（that）I have never been there.

The question is whether（不能用if）it is worth doing.

同

位

语

从

句The fact that she had not said anything surprised all of us.

They asked me the question whether the work was worth doing.

连接代词

主

语

从

句Who will help him is not known.

What he said is very important.

Which side will win is not clear.

宾

语

从

句

（1）作及物动词的宾语。例如：

I really don’t know what he is doing.

Do you know who/whom they are waiting for?

He asked whose dictionary it was.

He can’t tell which method they will use for the experiment.

（2）作介词的宾语。例如：

Pay attention to what the teacher said.

that who whom whose which

I wondered to whom he had given the letter.表

语

从

句

That is what he is worried about.

The question is who will come here.

The question is which team will win the match.

连接副词

where when why how

主

语

从

句Where she has gone is not known yet.

When they will start is not known yet.

Why he did it wasn’t quite clear.

How he became a great scientist is known to us all.

宾

语

从

句I don’t know where we are going to have the meeting.

Please tell me when we shall discuss our work plan.

Do you know why he said that?

Will you tell me how I can get to the railway station?

表

语

从

句That is where he was born.

This is why he is late.

This is how he did it.

The question is when he will be back.

同

位

语

从

句

I have no idea when he will come back.

You have no idea how worried I was.

The problem is where we can get so much money.

2.名词性从句的其它用法：

1）if不能引导表语从句。连接代词who、what、whose、which不能引导同位语从句。

2）有时as、as if/though、because也可以引导表语从句，能跟表语从句的谓语动词一般为系动词be、seem、look等。例如：

Things are not always as they seem to be.事情并不总是像表面上看来的那样。

It looks as if it were going to rain. It is because you eat too much.

3）介词宾语不可以用which来引导，而要用what来引导。例如：

We can learn what we did not know. He will talk to us about what he saw in the U.S.

4）连词that引导的名词性从句除能用在except、but、in后之外很少作介词的宾语，。其它一些介