同学你好，该知识点来自沪江网校《新概念英语2、3、4册连读【双11专享班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
see sb. do sth.表示看见某人做某事，强调看到某人做事的全过程。
see sb. doing sth.表示看到某人正在做某事，强调正在做。

I saw him get on the bus. 我看见他上了车了。
I saw a girl reading in the park. 我看见一个女孩正在公园里读书。

但是一般没有see sb to 结构，感官动词see，hear，feel，watch，notice，look at，listen to等，后常跟不带to的不定式作宾语补足语。例如：
A woman saw it happen when she was walking past. 一位妇女路过时看到(它掉下)了。
We often heard her sing in the next room. 我们经常听到她在隔壁唱歌。

注意：在被动语态句子中，不定式前必须加to. 例如：
He was made to do it. 他被迫做这件事。
She was often heard to sing in the next room. 经常听到她在隔壁唱歌。
He was once seen to come out of the place. 有一次有人瞅见他从这里走出来。

祝同学学习进步~