把下面几个句子改为被动语态在线等谢谢~
We don’t often speak English at home.
They didn’t cook meals yesterday.
We should obey the rules in our school.
The girls often sing English songs after class.
They can make this kind of machine in the fatory.The old man built a new house in front of the mountain.
Did you leave your key on the desk?
He will finish his new book next month.
They didn’t held the sports meeting because of the heavy rain.
They need 20 desks.
Must we clean the room?