名词性从句

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名词性从句

1. 名词性从句的定义

名词性从句是起名词作用的从句,这些从句可以作为一个整体来看,其作用就相当于一个名词,在复合句中作主语,宾语,表语和同位语。名词性从句包括主语从句,表语从句,宾语从句,同位语从句四种。

2. 名词性从句的连接词

名词性从句通常由一个连接词和主句相连。连接词很重要,它既是联系主句的纽带,又是从句的标志,通过连接词,我们可以辨认不同从句的性质。

一. 从属连接词(在从句中不充当任何成分,只起到连接从句的功能)

A. that 只是引导名词性从句,本身并没有实际意义,在从句中不充当任何句子成分。

That he will come to the meeting is certain.(主语从句)

The fact remains that we are behind the other group.(同位语从句)

B. if 和whether 具有“是否”的意义,但是whether比较正式,在口语中人们经常if, if 和whether在名词性从句中尽管不充当任何的成分,但不可以省略。

C. whether不能替代if的情况

1. if只能引导宾语从句(做介词宾语的情况除外),而whether 可以引导所有的名词性从句。

She asked if/ whether that was enough.

Whether the football match will be played depends on the whether.

The question is whether we can arrive there on bus.

2. whether引导宾语从句做介词的宾语,if没有这种用法

It depends on whether it will be fine.

3. whether后紧跟不定式

He was wondering whether to go home.

4. or not 可直接跟在whether后面,但不可以直接跟在if后面。

I don’t care if or not he has realized his mistakes.【错误】

I don’t care whether or not he has realized his mistakes.【正确】

I don’t care whether/if he has realized his mistakes or not.【正确】

5. 用if时会产生歧义的时候

Please let me know if you need my help.

if 被理解为“如果”的话,引导的就是条件状语从句。

if 被理解为“是否”的话,引导的就是宾语从句。

6. 在discuss 等某些动词之后,用whether

The students are discussing whether they can finish the work in time.

二. 连接代词(即起着连接作用,本身还在句中充当成分)

连接代词是具有代词的特点,同时又能引导从句的词,主要有what, whatever, who,

whoever, whom, whose, which, whichever等。这些词在从句中即做特定的成分(主语,宾语,表语,定语)又有具体的含义,不可省略。

What we should do with this problem is undecided.

The question is who we should trust.

She wonders whose fault that is.

Here are some reference books. Tell me which are worth reading.

使用连接代词whoever, whomever, whatever, whichever等用来引导名词性从句时,语气得以加强。(这种wh--+ever的形式不可引导做介词,形容词的宾语从句!)

注意下面的几种转换形式:

whatever anything that

whoever anyone who

whomever(作宾语一般使用它) anyone whom

whichever 无论哪一个(没有那种any的形式)

Whoever leaves the classroom should tell me.

You can give it to whomever(whoever)you like.

I’ll take whichever book interests me.(定语)

I just said whatever came into my head.

【目前,在实际的运用中,whomever 常被whoever所取代】

Tell whoever you like—it makes no difference to me.

Whoever you invite will be welcome.

三. 连接副词(即起着连接作用,本身又做从句的状语)

This is why she is so happy.

Where she has gone is not known yet..

Could you please show me how you read the operating directions?

各类连接词可以连接的从句类型

从句类型

主语从句 表语从句 宾语从句

同位语从句 连词 动词宾语 介词宾语 形容词宾语

从属连接词 that ● ● ● ● ● ●

if ● ●

whether ● ● ● ● ● ●

连接代词what 等 ● ● ● ● ● ●

连接副词when等 ● ● ● ● ● ●

wh-+ever ● ● ● ●

3. 主语从句

概念:在句中起主语作用的从句称为主语从句。

形式:1. 通常放在主句谓语动词之前

2. 用形式主语it替代,而从句则放在句子末尾

(1). 从属连接词引导的主语从句

A. that(在从句中不充当任何成分,通常that放在句首,不可省略)

That she will refuse the offer of help seems unlikely.

That you can’t match him at chess is not true, is it?

(斜体部分,是一个完整的句子,也就是说当直接在其后接seem,is这些动词,系动词时,是不可行的,需要加上that对这个句子的形式加以改变,使之由句子变为从句,才可充当主语)

B. whether (在句中不充当任何成分,不可用if代替)

Whether you will go outing depends on the weather.

Whether they will ever become future Olympic champions remains to be seen.

(2). 连接代词引导的主语从句

(who, whoever, whom, whomever, what ,whatever, whose, whosever, which,

whichever)

What I have seen last night has made a very deep impression on me.

Who made the long distance call is not important.

Whatever you have done is right in his eyes.

(3). 连接副词引导的主语从句

(when, whenever, where, wherever, how, however, why)

When they will come hasn’t been made public.

Why he did it will remain a puzzle for ever.

※ (2), (3)中的类型属于wh-类连接词,这类连接词引导的主语从句既可以放在句首,也可以放在句尾,放在句尾需要用形式主语替代wh-从句。

※ 用it做形式主语的主语从句

含有主语从句的复合句,如果主语从句太长,为避免句子结构头重脚轻,我们可以用it作形式主语,而把主语从句放在主句谓语部分之后,尤其是当主句的谓语动词是连系动词时。

几个常见的结构:

A. it +系动词+形容词(通常为单个形容词)+主语从句(一般情况下为that引导的从句)

It is likely that he can’t come to the party tonight.

It is obvious that you’ve made a big mistake.

It seems that you didn’t like the idea.

当形容词为necessary/important/surprising/strange/unthinkable/unbelievable/increcible/natural/possible等时,从句中用“(should)+动词原形”的形式

It is important that a college student (should) learn English well.

It is necessary that you (should) remember these words.

B. it+系动词+名词+主语从句(一般情况下为that引导的从句)

It is a pity that you didn’t attend Mary’s wedding.

It’s no wonder that you’re late again.

C. it+be+动词的-ed形式+主语从句(一般情况下为that引导的从句)

It is reported that no passengers were injured in the accident.