名词性从句简单讲解

名词性从句之异同

名词性从句可分别作主句的主语、宾语、表语和同位语,在英语阅读和运用中经常遇到，是高中英语中主要学习内容,。名词性从句在结构上有其许多相似之处,也有一些明显之区别。

一、名词性从句的相同之处

1. 关连词相同。

A）连词that，whether

B）连接代词who，what，which，whose

C）连接副词when，where，why，how

2．名词性从句均不能用逗号和主句分开。

二、名词性从句句法结构不同用法区别

1．主语从句能用it作形式上的主语。常用以it作形式主语的句型有：

①It + be + 形容词(obvious, true, natural, surprising, good, wonderful, funny, possible, likely, certain, probable, quite clear, unusual, etc.) + that从句。

如：It is certain that she will do well in her exam.

It is probable that he told her everything.

②It + be + 名词词组(no wonder, an honour, a good thing, a pity, no surprise, etc.) + that 从句。

如：It's a pity that we can't go.

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

③It + be + 过去分词(said, reported, thought, expected, decided, announced, arranged, etc.) + that从句。

如：It is said that Mr Green has arrived in Beijing.

It is reported that China has sent another man-made earth

satellite into orbit.

④It + seem, happen等不及物动词及短语+ that从句。

如: It seems that Alice is not coming to the party at all.

It happened that I was out that day.

⑤It + doesn't matter(makes no difference, etc.) + 连接代词或连接副词引起的主语从句。如：It doesn't matter whether she will come or not.

It makes no difference where we shall have the meeting.

⑥当that引导的主语从句出现在疑问句中时，要以it作形式主语而把主语从句后置。

如：Is it true that the scientist will give us a lecture next

week?

Does it matter much that they will not come tomorrow?

⑦连接代词whoever、whatever、whichever可引导主语从句。

例：Whoever comes will be welcome.

Whatever he did was right.

Whichever of you comes in will receive a prize.

1.如果宾语从句后还有宾语补足语，则用it作形式宾语而将宾语从句后置。

如：We thought it strange that Xiao Wang did not come yesterday.

He has made it clear that he will not give in.

2.作介词的宾语

连词that引导的名词从句很少作介词的宾语，只在except, but, besides介词后偶尔看到。其他一些介词的宾语从句如果由连词that引导，则需用it先行一步，作形式宾语。如：He is a good student except that he is careless.

You may depend on it that they will support you.

3.某些形容词或过去分词后常接宾语从句，这类形容词或过去分词有sure, glad, certain, pleased, happy, afraid, surprised, satisfied等,连词that可省略。有的语法书上把这种从句称为状语从句。

如：I am not sure what I ought to do.

I’m afraid you don’t understand what I said.

I’m surprised that I didn’t see all that before.

Mother was very pleased her daughter had passed the exams.

4.连词whether(...or not)或if引导的宾语从句

1)if和whether引导的宾语从句可以互换使用，但whether常和or not 连用，if则不习惯与or not 连用；宾语从句是否定句时，一般用if引导。

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

I don't care if(不能用whether) it doesn't rain.

2)用if引导宾语从句如果会引起歧义，应避免使用if而用whether。试比较：

Please let me know if you want to go.

Please let me know whether you want to go.

(if从句既可理解为宾语从句又可理解为条件状语从句。)

3)作介词的宾语只能用whether，不能用if。如：

Everything depends on whether we have enough experience.

5.介词宾语不可以用which来引导，而要用what来引导。

如：Are you sorry for what you've done?

6.宾语从句的否定转移。think, believe, suppose, expect等动词后宾语从句，有时谓语尽管是否定意思，却不用否定形式，而将think等动词变为否定形式。

如：I don't think you are right.

I don't believe they have finished their work yet.

I don't suppose he cares, does he?

He doesn't expect we need worry.

7.suggest, order, demand等动词后面的宾语从句要用虚拟语气。(可参阅虚拟语气的有关内容)

8. 连接代词whoever、whatever、whichever可引导宾语从句。

例：I'll show you whatever you want to see.

You may choose whoever you like.

I’ll take whichever fits the sockets(插座).

1.连词as if(好像, 仿佛) 引导表语从句(if不能引导表语从句)。能跟表语从句的谓语动词一般为系动词be, seem, look等。

如：It looked as if it was going to rain.

2.连词because可引导表语从句。

例：I think it is because you are doing too much.