同学你好，该知识点来自沪江网校《新概念英语1、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~
watch sth do，这里用不加to的不定式作宾补，比如
They watched the bus disappear into the distance.
他们注视着公共汽车消失在远方。

使役动词let，make，have等，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。


祝同学学习进步~