微课：动词不定式的基本用法归纳

微课视频：

什么是不定式：

不定式由“to+动词原形”构成,其否定形式是“not/never to do”,不定式可以带宾语或状语构成不定式短语,没有人称和数的变化,但有时态和语态的变化。不定式可以作主语、宾语、宾补、状语、表语和定语，但不能单独作谓语。不定式的逻辑主语有时用“for+名词或代词宾格”构成。

1. 不定式作主语   (subject)

(1)单个不定式作主语时,谓语动词用单数。

To see is to believe.

To keep smiling is healthy for you.

·Early to rise and early to bed is a good habit．

·When and where to hold the party hasn’t been decided.

·When to hold the party and where to hold  the party haven't been decided.

(2)若不定式太长,往往用it作形式主语,不定式后置。

It’s important to learn English well.

2.不定式作宾语

·1)．不定式作宾语的动词有许多，如want, decide, intend, expect, learn, manage, plan, promise, refuse,threaten, fail, wish, hope, pretend, choose等等。

· I mean to go there at once.

· I hope to finish the work in time.

· I plan to go to Beijing this summer.

·2).不定式短语作宾语时，如果还带有宾语补足语，往往把不定式短语放在宾补之后，而用it作形式宾语。句型为“主语+find (feel, think, believe,consider,etc) +it+形容词/名词+to do sth”。

· I think it our duty to obey the laws.

· I found it difficult to see him here. 

3.不定式作宾语补足语：

（1）Warn, tell, allow, help, ask, force等+sb to do sth

The teacher told me to clean the blackboard.

I expect you to give me some help.

（2）【注意】在感官动词（see,hear, feel, listen to , notice, watch, observe等）和使役动词let,have，make后的补足语中，不定式不带to。记忆口诀是：

4.不定式作定语

5.不定式作状语

6.不定式作表语

7.独立结构作状语

8.不定式与疑问词who,which,when, how, what，why等连用

9. 不定式的省略

以上6种用法详见上面的微课视频讲解。