动词不定式的一般形式是“to＋动词原形”,但在下面情况中to要省略：
一、在感官动词see,hear,watch,notice,feel,look at,listen to等及使役动词make,let,have等后作宾语补足语的动词不定式要省略to.如：
We saw him get on a bus.
The boss often made the workers work for over 12 hours a day.
注意：以上情况如果用于被动语态时,不定式符号to一定要补回.如：
He was seen to get on a bus.
The workers were often made to work over 12 hours a day.
二、在动词help后作宾语补足语的动词不定式符号to可带可不带.如：
I often help my mother (to) do housework.
三、在had better,would rather后动词不定式不能带to.如：
You’d better not go out at night.
The boy would rather stay at home by himself.
四、当两个或两个以上的动词不定式并列使用时,通常只有第一个不定式前带to,第二个及以后的不定式可省略to.如：
I want to have a read and write.
He wants to have a rest and have a cup of tea.
五、“Will(Would) you please＋不带to的不定式”.如：
Would you please not do that again?
六、当不定式作介词but,except的宾语,表示“除了……不/没有做……”时,不定式要省略to.如：
She does nothing but watch TV.
She doesn’t want to do anything except sleep.