不带to 的不定式:
在“动词+ 宾语+不定式”结构中, 如果动词是表示感觉意义的see, hear, watch, smell, feel, notice等, 或是表示“致使”意义的have, make, let等, 其后的不定式结构不带to.
John made her tell him everything.
这类结构转换为被动语态时, 后面的不带to 的不定式一般还原为带to 的不定式.
She was made to tell him everything.
在had better, had best, would rather, would sooner, would just as soon, might (just) as well, cannot but 等搭配之后, 动词不定式也不带to.
I'd rather not have eggs and bacon for breakfast.
They cannot but accept his term.
在make do, make believe, let drop, let fall, let fly, let slip, let drive, let go of, let there be, hear say, hear tell, leave go of等固定搭配中, 用不带to的动词不定式.
John let fly a torrent of abuse at me.
I've heard tell of him.
在动词help(或help +宾语)之后可用不带to的不定式, 也可用带to的不定式.
Can I help (to) lift this heavy box?
在介词except, but 之后, 如果其前有动词do的某种形式, 不定式一般不带to, 反之带to.
There is nothing to do except wait till it stops raining.
Smith will do anything but work on a farm.
There's no choice but to wait till it stops raining.
连词rather than, sooner than 置于句首时, 其后的不定式不带to.