$\text{⇒ Answer:}$

$\text{21. Ba suggested that chicken shouldn’t be eaten so that they could}$

$\text{avoid being infected with bird flu.}$

$\text{22. The teacher suggested that Ha Long Bay should be elected as}$

$\text{one of the World Wonders.}$

$\text{23. The room was filled by smoke.}$

$\text{24. We were let go (by they) yesterday.}$

$\text{25. I remember being taken to the zoo (by my father).}$

$\text{26.}$

$\text{- It is thought that he is living abroad.}$

$\text{- He is thought to be living abroad.}$

$\text{27. He calls his dog is Tony.}$

$\text{28. Bell invented the telephone.}$

$\text{29. They should encourage students to wear uniforms.}$

$\text{30. They is going to build the Thu Thiem Bridge soon.}$

21. be eaten to avoid infected with bird flu. 

22. should be elected as one of the World Wonder

23. was filled by smoke

24. We were let to go yesterday.

25. 

26. It is thought that he is living abroad

He is thought to be living abroad.

27. He has his dog which called Tony.

28. Bell invented the telephone.

29. They should encourage students to wear uniforms.

30. They is going to build the Thu Thiem Bridge soon.

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