请把一下主动句改被动句,
问题描述：
请把一下主动句改被动句,
they cleaned the classroom .
They showed me the room where they lived.
I did my homework.
The teacher is keeping the pupils at school for a revision.
In 1942 the *ers of war built this bridge.
答
The classroom was cleaned by them.
I was showed the room where they lived by them.
My homework was done by me.
The pupils are being kept at school for a revision by the teacher.
The bridge was built by the prisioners of war in 1942.