i can't but____hear such a storya.laughb.to laugh不是有but to do么?为什么这里没有to呢?

i can't but____hear such a storya.laughb.to laugh不是有but to do么?为什么这里没有to呢?
i can't but____hear such a story
a.laugh
b.to laugh
不是有but to do么?为什么这里没有to呢?

i can't but____hear such a storya.laughb.to laugh不是有but to do么?为什么这里没有to呢?
a.laugh是对的
句子前面有情态动词can't,只需用动词原形,不能再带to

前面有can 后面接原形