Làm giúp mình câu 11 đến câu 20

11. The boss made them work very hard.

⇒ They was made to work very hard by the boss.

12. They have just held an English workshop.

⇒ An English workshop has just been held.

13. The President of FIFA is awarding Suker the silver medal.

⇒ Suker is being awarded the silver medal by the President of FIFA.

14. Huong was reading '' Romeo and Juliet '' when we came.

⇒ '' Romeo and Juliet '' was being read by Huong when we came.

15. You must do this exercise carefully.

⇒ This exercise must be done carefully.

16. No one can answer this question.

⇒ This question can't be answered.

17. Mary's parents gave her a birthday present.

⇒ Mary was given a birthday present by her parents.

⇒ A birthday present was given for Mary by her parents.

18. Have they read the letter ?

⇒ Has the letter been read ?

19. Did they have to choose it ?

⇒ Did it have to be chosen ? 

20. Who wrote that play ?

⇒ Who was that play written by ?