一、 把下列句子變成被動語態(tài)：
1.They used recorders in English class.
-> Recorders are used by them in English class.
2.Have you posted the letters yet?
-> Have the letters been posted by you yet?
3.Can you do it tomorrow?
-> Can it be done tomorrow?
4.They must build another house to live in.
-> Another house must be built by them to live in.
5.He is writing a book for children.
-> A book is being written by him for children.
6.The teacher told the children a story.
-> The children were told a story by the teacher.
7.He will give you an excuse when you ask him to help you.
-> You will be given an excuse by him when he is asked by you to help you.
二、 把下列句子變成主動語態(tài)（用括號里的詞作主語）：
1.This song is often sung.(girl)
-> A girl often sings this song.
2.These photos were taken on the Great Wall.(Mr.Brown)
-> Mr.Brown took these photos on the Great Wall.
3.The room is being cleaned.(the boys)
-> The boys are cleaning the room.
4.A short play will be put on for the party.(we)
-> We will put on a short play for the party.
5.I was told her father had gone back home.(they)
-> They told me her father had gone back home.
6.Something must be done to save money.(we)
-> We must do something to save money.
7.The old house has been moved away.(some workers)
-> Some workers have moved away the old house.