英语语法学习：非谓语动词（动词不定式to do的用法）

#非谓语动词#

不定式的基本形式：to+动词原形，有时可以省略to。

这里的to是不定式符号，本身没有意义。

动词不定式的否定形式是“not+to do”。

① 作主语

动词不定式作主语时，常用it作形式主语，而将真正的主语放在句末，其结构为：

It+be+adj./n. (for/of sb.)+动词不定式。

例如：

To learn English well is useful.

=It is useful to learn English well.

It is a hard job for us to finish the work in such a short time.

It is kind of you to help me a lot.

② 作宾语

一些谓语动词后只能用不定式作宾语，常见的这类词表示命令、打算或希望，如：

would like, want, wish, hope, decide, plan, expect等。

如：

Would you like to see a film this evening?

注意：

在find, think后跟不定式作宾语时，常用it作形式宾语，而将真正的宾语放在后面。

I find it easy to read English every day.

③ 作宾语补足语

不定式作宾语补足语时与宾语有逻辑上的主动关系，常见的这类动词有tell, ask, want, allow, would like, encourage等。

Lucy asked him to turn down the radio.

注：

有一些使役动词和感官类动词也用不定式作宾补，这时不定式要省略to。常见的这类动词有：let, make, feel, hear, watch, see, notice等。

The boss made them work the whole night.

I saw the thief walk across the square.

④ 作定语

不定式作定语时，放在名词后面，两者构成逻辑上的动宾关系，如果不定式是不及物动词，且与被修饰的名词之间有被动关系，要在不定式后面加上适当的介词。

I want something to eat.

I need a pen to write with.

⑤ 作状语

不定式常用来表示目的，作目的状语，也可以在不定式前面加上in order或者so as。

To save time, we took the plane to Beijing.

I will write down the telephone number in order/so as not to forget it.