1.在句子中充当名词用的子句是名词子句。

2.名词子句可在句中作主语,也可用it作形式主语,而把作真正主语的名词子句放到句子的后面。

It is great that I have a friend like you.

我有你这样一个朋友，真是太棒了。

That he is the best student in the class is obvious.

他是班上最好的学生,这是显而易见的。

It is good that she studies hard.

她努力学习,这很好。

3.名词子句可在句中充当及物动词的宾语,常跟在know, say, ask, tell等动词后。

Now I want to know what I can do.

现在我想知道我能做什么。

I don't know whether he has arrived.

我不知道他是否已经到了。

4.名词子句可在句中充当介系词的宾语。

I ?m thinking about what I should do.

我正在思考我应该做什么。

He began to think about what he would do.

他开始思考他要做什么。

5.名词子句可充当补语。

The problem is that he is too young.

问题是他太年轻。

6.名词子句可以作同位语。

I＇ll face the fact that my girlfriend will come this afternoon.

我将要面对我女友今天下午要来的事实。

名词片语that my girlfriend will come this afternoon作主语的同位语。 

The fact that she is ill should be considered.

应该考虑她生病这一事实。

名词片语that she is ill作主语的同位语。

I don't know the news that he has been elected chairman.

我不知道他已当选主席的消息。

名词片语that he has been elected chairman作宾语同位语。

7.名词子句中语序不可倒置。

I don't know what did he say.(误)

I don't know what he said.(正)

我不知他说了些什么。

8名词子句表现礼貌。

What time is it?

现在几点了？

Could you tell me what time it is?

请告诉我现在几点钟了。