举个例子来说吧I saw him play football on the playground just now.变成被动语态应该是He was seen to play football on the playground just now.
I saw him playing football when I passed the playground.变成被动语态应该是He was seen playing football when I passed the playground.
see 是感官动词,在变成被动语态时to 不能省略,这个to是动词不定式的标志,跟接动名词形式不是一回事,动名词 不是不定式,为什么非要接to呢