省TO不定式的情况

1） 情态动词 ( 除ought 外，ought to)： You can do it!

2） 使役动词 let, have, make：

My brother has me do his work. My sister helps me buy a ticket. Let's go. Let me try.

3） 感官动词 see, watch, look at, notice , observe, hear, listen to, smell, feel, find 等后作宾补，省略to。

注意：在被动语态中to 不能省掉。

I saw him dance. The boss made them work the whole night. =He was seen to dance. =They were made to work the whole night.

4） would rather，had better：

You had better go now你最好现在就走

He'd(=He had) better do it now他最好现在做 She'd better not cry她最好别哭

5） Why… / why not…：

例：---- I usually go there by train.

---- Why not ___ by boat for a change?

A. to try going B.trying to go C.to try and go D.try going 答案：D. why not 后面接不带to 的不定式，因此选D。

6） help 可带to，也可不带to, help sb (to) do sth：

例：Mother helped me（to） do my homework．妈妈帮助我做家庭作业。

7） but和except：but前是动词do时，后面出现的动词用不带to的动词不定式。

例：He wants to do nothing but go out. 8） 由and, or和than连接的两个不定式，第二个to 可以省去： 9） 通常在discover, imagine, suppose, think, understand等词后，可以省去to be：

He is supposed (to be) nice. 他应该是个好人。