高中英语语法--名词性从句专项讲解及训练

名词性从句

名词性从句

一．概述：在句子中起名词作用的各种从句统称为名词性从句。根据它们在句中的语法作用，这类从句又可分为主语从句、表语从句、宾语从句和同位语从句。

四．if, whether的区别

1.引导主语从句时，如果主语从句放在句首，只能用whether不能用if引导，但是如果用it 做形式主语，而把主语从句放在句末时，也可以用if引导.

2.引导宾语从句时常放在动词know, ask, care, wonder之后，if和whether均可。

3.在介词后面的宾语从句中，在表语从句、同位语从句中，表“是否”，只能用whether；

4.whether和if都可以和or not连用,但是whether 之后可以直接跟or not,而if不可以。I don’t know whether or not I will stay.（只能用whether）

5.在不定式前只能用whether.

如：I can’t decide whether to stay. 我不能决定是否留下。

五．与“命令、要求、建议”等相关的名词性从句中通常用虚拟语气，虚拟语气的构成是“should＋动词原形”或省去should，直接用动词原形。

六．名词性从句以考查引导词为主，同时考查时态，语序，与其它从句的区别以及混同虚拟语气的考查。

一．主语从句

1.主语从句定义：在复合句中充当主语的句子叫做主语从句。

That he will succeed is certain.

Whether wild life can be well protected is of great importance.

Who will go makes no different.

Which kind of food is the best is still not certain.

What is needed for the space trip is careful preparation.

How we can help the twins will be discussed at the meeting.

When they’ll start the project has not been decided yet.

Where he hid the money is to be found out.

Why dinosaurs died out remains a puzzle.

2.主语从句引导词按照在句中是否做成分主要分为三类：连词that、whether、if 连接代词、连接副词。

（1）由连词that引导的主语从句:引导词that无含义,在句中不做成分,

That you will win the medal seems unlikely.

That you are so indifferent bothers me.

It was a pity (that) you didn’t go to the talk. 很遗憾你没去听报告。(that可省)

（2）由连词whether 引导的主语从句：whether有含义“是否”，在句中不做成分，不可以省。whether 可以和or not连用。

Whether it will do us harm remains to be seen.

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

（3）如果主语从句放在句首，不能用if引导，但是如果用it 做形式主语，而把主语从句放在句末时，也可以用if引导.

Whether Mary really heard him is really doubtful.（对）

It was doubtful if Mary really heard him.（对）

（4）连接代词引导的主语从句：连接代词who, whose, whom, which, what, whoever, whomever, whichever, whatever，在句子起名词性作用，担当一定成分。Who killed the scientist remains a question.

Whom she borrowed money from still puzzled him.

Which side will win is not clear.

What you need is more practice.

Whoever breaks the law will be punished. (主语从句)

= Anyone who breaks the law will be punished. (定语从句)

比较：Whoever breaks the law，he should be punished.(让步状语从句)

= No matter who breaks the law，he should be punished. (让步状语从句)

（4）用连接副词when, where, why, how引导的名词性从句(其连接副词有含义,在句中作状语。)

Where we should leave it is a problem.

When they will come hasn’t been made pubic.

How it was done was a mystery.

3.主语从句注意事项

（1）为了避免主语冗长,句子头重脚轻,经常用it 做形式主语,而将主语从句置后（尤其是当谓语较短时）。

①That light travels in straight lines is known to all.

=It is known to all that light travels in straight lines.

①Whether they would support us was a problem.

=It was a problem whether they would support us.

（3）连接代词What引导的名词性从句

①what引导主语从句时，常常翻译为“所…….的”或“…..的事物/东西/人/样子/地方等”此时无疑问含义。What在从句中作主语，宾语。

What you need is a good-sized canvas bag.

What make the river more beautiful are the lotus(荷花) plants growing in the water.

①what引导主语从句时，谓语动词常与其后的作表语的名词一致。

What you left are only several old books.

What you said is of great importance.