不定式中的to的省略情况不定式中的to的省略情况

1．感官动词feel, hear, listen to, see, look at, notice, observe, watch及使役动词have, make, let带动词不定式作宾语补足语时，to省略。但是，当这些词用在被动语态的结构时，to就不能省略，例句。

The boy always makes the little girl cry on their way home from school.

The little girl is always made to cry on their way home from school by the boy.

动词不定式作其它成分（主语、宾语、定语、状语、表语）时，to 不省略。

2．不定式用作介词but和except 的宾语时，如果前面是谓语动词do的各种形式，to省略。否则不定式应带to。例如：

I could do nothing but help him with the work.

He did everything at home last night except cook the meal.

We have no choice but to fight to win or to die.

另外，还有：can not (help/choose) but do …（不得不），can do nothing but … 和can not do anything but do… （只能做）也不带to。例如：

The bus has left. I can not help but wait.

3．当两个或多个带to的不定式由并列连词and或or连接在一起时，第二个to可省略；但是，如果不定式之间不是表示并列，而是表示强烈的对比关系，或者在不用and或or连接时，第二个to不省略，例如：

He decided to go to school and ask his teacher for help.

I came here to help you, but not to make trouble.

4．含有do的名词性从句作句子的主语，或者是all/thing + 定语从句时，后面作表语的不定式可以带to，也可以不带to；如果不是含有do，则应带to。例如：

What he wanted to do is (to) have a good sleep.

All I do is (to) help my mother with the cleaning of the floor.

What the workers would demand is to raise their wages.

5．在had better, rather than, would rather… than, might as well等结构中的不定式不带to，动词help后面的不定式可带也可不带to，例如：

Rather than ride on a crowded bus, he always prefers to ride a bicycle.

Fast development of new technology helps communicate with each other easily.