56. The tree looked really nice after they finished ______ it .

　　 A. decorate　　　　　　 B. decorating　　　　 C. decorated　　　　　 D. to decorate

55. Do scientists always count __________ their fingers?

54. Go __________ the stationers and get some stationery.

53. These cakes taste __________ cement.

52. It's nice __________ you to take him __________ hospital.

51. It's difficult __________ them to study English because they aren't interested __________ it.

50. What do you mean __________ the word "stupid"? It's another way __________ saying "foolish".

49. How did you travel? We travelled __________ air.

48. He came in __________ a smile __________ his face.

47. What were you doing when Helen called __________ see you last week? I was __________ the greengrocer's.