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 ?
