40. Robert is said ______ abroad, but I don’t know what country he once studied in.

　 A. to have studied　 B. to study　　 C. to be studying　　 D. to have been studying

39. The reason why he has been such a success ____ he never gives up. 　 A. is what　　 　 　B. is that　　　　　 C. is because　　 　　D. is why

38. ---- ____ that he managed to get the information?

　 ----Oh, a friend of his helped him.

　 A. Where was it　 B. What was it　 C. How was it　 D. Why was it

37. In order to make our city green, _____.

A. it is necessary to have planted more trees　 B. many more trees need to plant

C. our city needs more trees.　　　　　　　 D. we must plant more trees