54.　　　 ______ the cat family, the small tiger looks like a big cat.

A. being at　 B. belonged to　 C. in　 D. belonging to

53.　　　 ---- I don’t understand that sentence let’s get tom ____ the sentence again.

A. explain　 B. to explain　 C. explained　 D. explaining

52. --- I must apologize for　 ____ ahead of time.

　 --- That’s all right.

A. letting you not know　　 B　 not letting you know　

C letting you know not　　　 D letting not you know

51. Rather than ____ on a crowded bus, he always prefers ____ a bicycle.

A. ride, ride　 B. riding, ride　 C. ride, to ride　 D. to ride, riding

50. The missing boys were last seen ____ near the river.

A. playing　 B. to be playing　 C. play　 D. to play

49. She set out soon after dark ____ home an hour later.

A. arriving　 B. to arrive　 C. having arrived　 D. and arrived

48. The first textbooks ____ for teaching English as a foreign language came out in the 16^th century.

A .having written　 B. to be written　 C. being written　 D. written

47. The visiting minister expressed his satisfaction with his talks, ____ that he has enjoyed his stay here.

A. having added　 B. to add　 C. adding　 D. added

46. _____ down the radio ---- the baby’s asleep in the next room.

A. turning　 B. to turn　 C. turned　 D. turn

45. How about the two of us ___ a walk down the garden?

A. to take　　 B. take　 C. taking　 D. to be taking