Change into the passive voice

15. Flowers can be found in almost every part of the world.

16. I was given a new pair of jeans by my sister on my fifteenth birthday.

17. A supermarket is being built on our street by the workers.

18. The animals are fed by the zookeepers twice a day.

19. Their car has been sold to pay their debt.

20. Flowers are going to be grown in the front yard.

21. This machine mustn't be used after 5.30 pm.

22. A new sweater is being knitted for me by my grandmother.

23. Were jeans made two hundred years ago?

24. This kind of cloth isn't used to make shirt.

25. The unique and fashionable Ao Dai is continued to be worn by Vietnamese women.

26. Many young people are attracted by these jeans.

27. The raincoat was returned to me by him.

28. You will be met at the station by my brother.

29. The homework hasn't been finished by John.

30. Everything for the meeting is being prepared by Mary.

* Cấu trúc câu bị động đầy đủ: S + be + V(pp) + từ chỉ nơi chốn + by O + từ chỉ thời gian.