31. B doesn't come ( if 1: If + S1 + Vs/es, S2 + will + Vinf )

32. D pollutants ( chất gây ô nhiễm )

33. B opening ( mind + Ving )

34. C to get ( ask + SO + to V )

35. A used to ( used to Vinf: đã từng )

III

36. go ( often: hiện tại đơn )

37. Have - eaten ( yet : hiện tại hoàn thành )

38. are playing ( look: hiện tại tiếp diễn )

39. was written ( bị động quá khứ đơn: S + was/were + Vpp )

40. hearing ( look forward to Ving )

IV

41. D aren't you -> are you ( tag question )

42. B walk -> walking ( suggest + Ving )

43. C friend -> friends ( many + N số nhiều )

44. A giving -> give ( used to Vinf )

45. B which -> who ( that cho người )

V

46. C had

47. A for

48. D is

49. D because

50. A to

51. D by

52. B at

53. D weekend

54. B longer

31, B - doesn't come.

32, D - pollutants.

33, B - opening.

34, C - to get.

35, A - used to.

36, go

37, Have you eaten

38, are playing

39, was written

40, hearing

41, D  aren't you -> are you.

42, A  walk-> walking.

43, C  friend -> friends.

44, A giving -> gives.

45, B  which -> who.

46, C - had

47, A - for

48, B - was

49, D - because

50, A - to

51, D - by

52, B - at

53, A - sands

54, D - weekend

55, B - longer