51. A. could B. couldn’t C. had to D. didn’t have to
50. A. riding B. running C. walking D. falling
49. A. teaches B. taught C. is teaching D. had taught
48. A. cheer up B. keep quiet C. enjoy yourself D. keep away
47. A. something B. anything C. everything D. nothing
46. A. hope B. promise C. wish D. agree
45. A. bus B. ship C. train D. flight
44. A. me B. him C. myself D. himself
43. A. word B. noise C. voice D. sound
42. A. leaving B. coming C. traveling D. returning