1. chuyển các câu sau sang bị động
1. they feed the dogs and cats every day
2. students must do their homework before class
3. he has just sent me a greeting card on my fifteenth birthday
4. Nobody has used this room for ages
5. you must clean the walls before you paint them
6. tom broke the windows and the teacher punished him
7. did columbus discover america?
8. where will they construct a new school?
9. In which countries do they speak english?
10. they are decorating metro supermarket for christmas and new year