13.The cats were fed by Ann before she went to the cinema.
14.Were the pollution discussed problems at school (by the students)?
15.Has the most valuable paiting in the national museum been stolen by the thieves?
16.How many languages are spoken in Canada(by them)?
17.Was the man seen by you?
Chúc bạn học tốt!Nếu được cho mình xin CTLHN nha!