see sb. doing 换成被动式怎么就成了be seen to do 而不是be seen doing ？

Question

如：He is often seen to read English in the morning .

Answer 1

被动式的结构是：
be + 动词的ed
see sb
被动
sb be seen
see sb doing
被动
sb be seen doing
doing是宾语补足语，形式永远不变。
很高兴为你解答！
老师祝你学习进步！
望采纳，多谢你的问题！^_^

Answer 2

记住吧 它就是这么定义的 没得解释