名词性从句讲义

名词性从句

一，名词性从句的概念：

1, 相当于名词，分为主语从句、表语从句、宾语从句和同位语从句

2，名词性从句的引导词：

that, whether, if (一般是宾语从句)，as if(表语从句)，who, whom, whose, what, which, when, where, why, how,以及由how组成的词组，如：how many, how long, how far

两组需要注意的连接词

that/what

1）that和what都可以引导名词性从句，但that是连接词，本身无词义，仅起连接作用，不在从句中担任任何成份；what是连接代词，不仅引导名词性从句，而且在从句中充当一定的成份，如主语、宾语或表语。

e.g: That he stole a bike was true.

The important thing is what you do, but not what you say.

高考真题：

_______ we can't get seems better than _______ we have.

A. What; what

B. What; that

C. That; that

D. That; what

2）whether和if均可引导动词后的宾语从句，常可互换。

a.在介词后面只能用whether，不能用if。

例如：①This depends upon whether we are determined to do it.

b.在动词不定式之前，只能用whether，不能用if。

例如：①He doesn't know whether to stay or not.

c.引导主语从句，表语从句，同位语从句时只能用whether。

例如：①It is unknown whether he will come. 他是否来还不知道。

②The question is whether they can take our advice.

3.The question whether he'll come is unknown.

3）doubt用于肯定结构时，后面用whether/ if引导名词性从句；用于否定结构或疑问结构时，后面用that引导名词性从句。be sure 用于肯定句或疑问句时，后接that引导的名词性从句；用于否定句时，后接whether/ if引导的名词性从句。

e.g：We doubt whether/ if he can win the game.

二，各从句的使用及注意事项

（一）主语从句：

1.充当主语的句子即主语从句。

（That he will come）is certain.

（Which team will win the match）is a matter of public concern.

2.名从的数：

1）用一个句子做主语时谓语动词用单数：

e.g: What you said ____ always right.

2) 主语连接的是两个或者两个以上的从句时，谓语动词用复数

e.g：When we will start and where we will go ___(have) not been decided yet.

3）主语连接的是两个或两个以上的连接词时，谓语动词用单数。

e.g：When and where we will go ___ (have) not been decided yet.

3.形式主语：

主语较长时，多在句子的后面，用it为形式主语。主要是：

It + be + adj + that

e.g：It is probable that he told her everything.

It + be + n + that

It is no surprise that our team should have won the game.

It + be + p.p + that

It is said that Jack drives badly.

It + seem/happen + that

It seems that Alice is not coming to the party.

☆：主语从句that不能省略。只可用whether不用if。

（二）表语从句

1,表语从句放在系动词之后

2,系动词：be动词，感动词，表动词

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

It looks （as if it were going to rain.）

3，as/as if/as though引导的表语从句常跟在特定动词后面，

如seem，appear，look，taste，sound，feel等。如：

①It sounds as if someone is knocking at the door．听上去好像有人在敲门。

②At that time，it seemed as th ough I couldn’t think of the right word．当时我似乎怎么也想不出一个恰当的字眼来。

（三）宾语从句

1,宾语从句放在动词介词之后：

Do you think （my clothes fit well?）(动宾)

Are you sorry for （what you’ve done?）(介宾)

2，时态一致原则

1）如果主句谓语动词为现在时或将来时，从句中的谓语可以不受影响，根据具体的情况来定。

e.g：Has he told you when he received the gift？

Will you tell me how you two are getting along？

2）如果主语谓语动词为过去时，从句谓语一般要跟着改为相应的过去时。

e.g：I didn＇t know where they lived. He thought he was working for the people. Asked him

how long he had been waiting.

3）当宾语从句表示永恒真理时谓语可以不变

e.g：This proved that the earth is round.

3，另外有形式宾语it的形式。

We thought it strange that Mike did not come yesterday.