Chuyển sang câu bị động
1. The students may use dictionaries during the test
2. Someone must teach that a boy a lesson
3. They don't sell stamp in bookshops
4. They make these artificial flowers of silk
5. Over a thousand people use this swimming pool each week
6. They sang the church bell as a flood warning
7. The knocked down the old house on the corner last year
8. Someone has taken my books away
9. They have seen this film many times
10. All of my students are doing a lot of homework now
11. They are building a new hotel near the park
12. Has she bought these pills at the drugstore?