$\text{⇒ Answer:}$
$\text{21. Ba suggested that chicken shouldn’t be eaten so that they could}$
$\text{avoid being infected with bird flu.}$
$\text{22. The teacher suggested that Ha Long Bay should be elected as}$
$\text{one of the World Wonders.}$
$\text{23. The room was filled by smoke.}$
$\text{24. We were let go (by they) yesterday.}$
$\text{25. I remember being taken to the zoo (by my father).}$
$\text{26.}$
$\text{- It is thought that he is living abroad.}$
$\text{- He is thought to be living abroad.}$
$\text{27. He calls his dog is Tony.}$
$\text{28. Bell invented the telephone.}$
$\text{29. They should encourage students to wear uniforms.}$
$\text{30. They is going to build the Thu Thiem Bridge soon.}$
