50.He reads newspapers every day to keep himself ____about what's going on in the world.　　　　　　　　　　　　　　　　　　　　　　 　A.inform　 　 B.informing 　C.informed 　 D.being informed　

49.He wrote a letter to me ____　that his trip to Japan had been put off because of the bad weather　　　　　　　　　　　　　　　　 　A.inform 　　 B.informing 　C.informed 　D.being imformed

48.　 ____a satisfactory operation, the doctor believed the patient would recover from his illness very soon.　　　　　　　　　　　　　　　　　 　A.Having been given　 B.Having given 　C.Giving 　　D.Being given

47. ____a satisfactory operation, the patient recovered from illness very quickly.　　　　　　　　　　　　　　　　　　　　　　　 　A.Having been given　 B.Having given 　C.Giving 　 D.Being given

46.When I came in, I saw Dr. Li　____a patient.　　　　　　　 　A.examine　　 B.examining　　 C.to examine　　 D.examined

45.The cars ____in Beijing are as good as those ____in Shanghai. 　　　　　　　　　　　　　　　　　　　　　 　A.produce, produce 　 B.produced, produced 　C.produced, producing　 D.producing, producing

44.The graduating students are busy ____material for their reports.　　 　A.collect　　 B.to collect　　 C.collected　　 D.collecting

43.I had to shout to make myself ____above the noise.　　　　　　 　A.heard　　 B.hearing　　 C.heard　　 D.to hear

42.He walked down the hills, ____softly to himself.　　　　　　　 　A.sing　　 B.singing　　 C.sung　　 D.to sing

41.At this moment the bell rang ____　the end of class.　　　　　　 　A.announce　　 B.announcing　　 C.announced　　 D.to announce