1. They must do their task now. 2. He expected me to buy him a book. 3. They want him to invite them to the party. 4. They opened the road 10 years ago. 5. He can mend all chairs for you now. 6. We expected them to forgive us. 7. They allowed women to vote many years ago. 8. You should open the wine 3 hours before you use it. 9. They think she is the most beautiful girl. 10. He had the neighbor mend the chair. 11. The walls need painting. 12. People say he is very rich. 13. I am going to ask the gardener to cut my fence tomorrow. 14. He neednt repair the bike. 15. People think he was an artist. 16. People said she was very intelligent. 17. Tom used to borrow my pen. 18. He had to finish his work on time. 19. You needn't do all the homework. 20. You ought to tell him early. 21. They don't use the room very often.

Công thức bị động thì HTĐ : S + is/am /are + V (ed/ c3) + ( by S ) 

thì QKĐ: S + was/ were + V(Ed/ c3) + ( by S )

bị động nhờ vả: S + have/get + sb + Vnt/ to V + sth

= S have/ get + sth + V(ed/c3) +( by S)

bị động đặc biệt: S + believe/ think/... + that + S2 + V + O

= It + be + believed/ thought/... + that + S2 + V + O

= S2 + be+ believed/ thought/... + to Vnt/ have V(ed/c3)

bị động khuyết thiếu: S + ought to/ should/can/... + be + V(ed/ c3)

1, their tasks must be done now

2, I was ecpected to buy him a book

3, He is wanted to invite them to the party

4, the road was opened 10 years ago

5, all chairs can be mended for you now

6, They were expected to forgive us

7, women were allowed to vote many years ago

8, the wine should be opened 3 hours before it is used

9, she is thought to be the most beautiful girl

10, He had the chair mended by the neighbor 

11, The walls need to be painted

12, he is said to be very rich

13, i am going to have my fence cut by the gardener tomorrow

14, the bike needn't be repaired

15, he is thought to have been an artist

16, she was said to have been very intelligent

17, My pen used to be borrowed by Tom

18, his work had to be finished on time

19, all the homework needn't be done

20, He ought be told early

21, the room isn't be used very often