see sb. doing sth.看見某人正在做某事的被動語態就是：sb be seen doing sth例如：Huruixin was seen copying the homework
see的被動語態爲seen.
例句：We saw him play football on the playground.--> He was seen to play football on the playground.
see，watch，notice，hear，feel，observe等這些在被動語態裏都要還原to，這些動詞都是及物動詞，有被動語態的.它們後面不帶to 的不定式在被動語態中都要將to 還原.例如：We often see him play basketball .-----He is often seen to play basketball by us. feel 可以做及物動詞，也可以做不及物動詞。當feel 做及物動詞時可以用被動語態。
例如：I can feel a nail in my shoe.我感到鞋裏有一顆釘子。 ---A nail can be felt (by me) in my shoe.
