Chuyển từ câu chủ động sang câu bị động :
1. How many ways can you solve this problem?
How many ways can this problem be solved by you ?
2. She did not use to make cloth puppets.
cloth puppets weren't used to made by her.
3. They must report it to the police ỏ it will be too late .
it must be report to the police by them or it will be too late.