Unit 1 语法重点

一、动词不定式

不定式可以用来做主语、表语、定语、状语、宾语、独立成分，表示比较具体的意义。

（1）做主语

① 动词不定式短语

To master a foreign language is no easy job.

To see this film is to waste time.

To solve this problem is out of the question

② 为平衡整个句子，避免头重脚轻，常用it做形式主语，而将真正主语不定式放后

面，用于这种形式是一些特定的结构。例如：

1）谓语部分是系表结构，表语是某些形容词或名词。例如：

It is foolish to do in this way. It sounds reasonable to do it this way.

2）某些动词做谓语时。例如：

It took much time to do this. It makes us excited to think about that.

(2) 做表语

表示打算、计划、命令和要求，用于appear, seem, happen等系动词后面

Such questions are to be avoided. What he said proved to be true.

He seems to be ill.

(3) 做定语

做定语时不定式一般紧跟其所修饰名词或代词后面。例如：

to come this morning.

He didn’t have the to go to school in the past.

如果不定式是不及物动词时，应注意其相应介词的搭配。例如：

to worry about.

to work with.

(4) 作状语

不定式作状语可以表示目的、原因和结果。

① 表目的常用in order to, so as to,等结构但so as to只能放在主句之后。

Check your homework so as to avoid mistakes.

She goes home (in order) to see her grandmother every week.

② 表结果常用only to do, enough to do, too…to do等句型，不定式短语作结果状语具有

“意料之外”之意。

He is too excited to speak anything.

I hurried to his house, only to find him out.

③原因

She seemed surprised to see us.

He is sorry for what he did to think of his past.

-不定式作方式状语时，通常采用as if 或 as though + to 的结构，其意为“好像要……”。

He raised his hand as if to hit me.

She took out a pen and a piece of paper as though to write something.

(5) 做宾语