把下列主动语态改为被动语态：when did they build the house?hav把下列主动语态改为被动语态：when did they build the house?have they posted the letter yet?we often see him help his classmate.they will say nothing more about hi

Question

把下列主动语态改为被动语态：when did they build the house?hav
把下列主动语态改为被动语态：
when did they build the house?
have they posted the letter yet?
we often see him help his classmate.
they will say nothing more about his matter.

Answer 1

When was the house built?
Has the letter been posted?
He is often seen to(注意这个to一定不可以省略) help his classmate.
Nothing more about his matter will be said by them.