1) 情态动词 ( 除ought 外,ought to):
2) 使役动词:let、have、make:
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:在被动语态中则to 不能省掉。
I saw him dance.
=He was seen to dance.
The boss made them work the whole night.
=They were made to work the whole night.
4) would rather、had better。
5) Why… / why not…。
6) help 可带to,也可不带to, help sb (to) do sth。
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。
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。
举例:
He wants to move to France and marry the girl.
He wants to do nothing but go out.
比较:
He wants to do nothing but go out.
He wants to believe anything but to take the medicine.
例题:
1) - 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。
解析:why not 后面接不带to 的不定式,因此选D。
2) Paul doesn't have to be made ______. He always works hard.
A. learn;B. to learn;C. learned;D. learning;
答案:B。
解析:make后接不带to 的动词不定式,当其用于被动时,to 不可省略。