42. The doctor did _______ to save his brother’s life.

A. all what he could　　 　　　　　　　B. as much as possible

C. all could be done　　　 　　　　　　　 D. as much as could

41. Our elder son has been ______ Africa for several months.

　 A. knocking about　　 B. knocking down　 　 C. knocking over　　　　　　　 D. knocking off

40. _____ he would have succeeded in the exams.

A. If he has worked hard　　　 　　　　　 B. If he works hard

C. Did he work hard　　　 　　　　　 D. Had he worked hard