20. The meeting has been cancelled. (S + have/has + been + Vpp + by O)

21. All the students in the school have been invited.

22. All the letters were posted yesterday. (S + were/was + Vpp + by O)

23. Two children were found in the forest by the police.

24. A meeting will be held before May Day. (S + will be + Vpp + by O)

25. The cake is being cut with a sharp knife by Mary. (S + is/are/am + being + Vpp + by O)

26. A story is going to be told by the teacher. ( S + is/are/am + going to be + Vpp + by O)

27. The town was destroyed by an earthquake.

28. The letter wasn't typed by him last night.

29. I will be picked up at my house.

30. When was he seen in that bank?

$\text{20.}$ The meeting has been cancelled.

$\text{→}$ S + have/ has + been + Ved/ P2 + (by): thì HTHT

$\text{21.}$ All the students in the school have been invited by us.

$\text{22.}$ All the letters were posted yesterday.

$\text{→}$ S + was/ were + Ved/ P2 + (by): thì QKD

$\text{23.}$ 2 children have been found in the forest by the police.

$\text{24.}$ The meeting will be hold before May Day.

$\text{→}$ S + will be + Ved/ P2 + (by): thì TLD

$\text{25.}$ The cake is being cut with a sharp knife by Mary.

$\text{→}$ S + is/ are + being + Ved/P2 + (by): thì HTTD

$\text{26.}$ A story is going to be told by the teacher.

$\text{→}$ S + Modal V + be + Ved/ P2 + (by)

$\text{27.}$ The town was destroyed by an earthquake.

$\text{28.}$ The letter wasn't typed by him last night.

$\text{29.}$ I will be picked up at my house.

$\text{30.}$ When was he seen in that bank by you?