Question

动词不定式做主语补足语的句式结构及例句

Answer 1

sth/sb be said / reported / thought / believed / known / supposed + to do sth.
在不定式做宾补的结构中，把它变成被动语态中，宾补就做成主补
I wish you to study English well.(宾补)
You are wished to study English.(主补)
The doctor warned you not to eat too much meat. (宾补)
You were warned not to eat too much meat.(主补)
2.make /hear/see/observe /watch sb do sth 感官动词和使役动词 用省略to的不定式作宾补，变成被动语态是 不定式变成主补，to恢复
I heard someone come up the stairs.(宾补)
Someone was heard to come up stairs..(主补)
He always makes me cry..(宾补)
I am always made to cry..(主补)

Answer 2

常用不定式做主语补足语的句型有：be said / reported / thought / believed / known / supposed + to do sth.
eg：You are supposed to ask your teacher if you want to leave the classroom.

追问

为什么主语后都是被动语态啊