33. Let's use bicycle or public buses.
-> I suggest using  bicycle or public buses.
+ How about using  bicycle or public buses?
B4. I can't find the answers to these questions.
->I wish I could find the answers to these questions.
35. "I must leave now, "said Mr. Quang.
-> Mr Quang said he must leave then 
36. Keith certainly can't be held responsible for the accident.
-> In no way Keith can be held responsible for the accident.
37. I like reading books. Books tell us about different people and their cultures. (which)
-> I like reading books which  tell us about different people and their cultures.
38. He is very intelligent. He can solve all these problems. (enough) 
->He is intelligent enough to  solve all these problems
39. You don't try to work hard. You will fall in the exam. (Unless)
->Unless you try  to work hard,you will fall in the exam
40. The Prime Minister set up a committee of financial experts. They were to help him discuss and formulate policies. (
=> The Prime Minister set up a committee of financial experts in order to help him discuss and formulate policies.