“特殊疑问词＋动词不定式”的用法归纳

　　一、疑问代词who, what, which等和疑问副词when, where, how等后面跟不定式，构成不定式短语。这种结构在句中可作主语、宾语、表语、宾语补足语等句子成分。如：

1. Where to go is still a question. 到哪里去还是个问题。（作主语）

2. I know where to find the boy. 我知道到哪里能找到这个男孩。（作动词know的宾语）

3. We must first solve the problem of whom to serve.

　我们必须首先解决为谁服务的问题。（作介词of的宾语）

4. The question is how to learn English well.

  问题是怎样学好英语。（作表语）

5. I asked her how to learn English. 我问她如何学英语。（用宾语）

二、“特殊疑问词＋动词不定式”结构经常用在某些动词后作宾语，类似的动词有：tell, show, know, learn, teach, find out, forget, wonder, remember等。如：

I’ll show you how to do it. 我要让你看看如何做这件事。

You’d better find out where to put it. 你最好弄清楚要把它放在哪里。

三、“特殊疑问词＋动词不定式”这种结构可以把复合句转为简单句。如：

I don’t know what I’ll do next. = I don’t know what to do next.

The doctor told him when he should take the medicine.

=The doctor told him when to take the medicine.

同样，因为“特殊疑问词＋动词不定式”这种结构相当于一个名词性从句，所以可用同等成分的从句代替，从而把简单句转换为复合句。改写时只需在疑问词后加上适当的主语，并把不定式改为适当的形式的谓语即可。如：

Li Ping doesn’t know why to learn English.

= Li Ping doesn’t know why he should learn English.

Which to choose is important. = Which we should choose is important.

The question is where to go. = The question is where we should go.

四、“特殊疑问词＋动词不定式”这种结构可构成独立问句。如：

What to do? 怎么办？

How to get rid of the trouble? 如何摆脱困境？