41. D. They haven't visited me for five years.
`->` S + last + V2/ed + thời gian + ago = S + have/has + not + Vpp + for + thời gian
42. A Before Mike went to bed, he had turned off the light.
`->` Before + quá khứ đơn, quá khứ hoàn thành
43. D. It is three months since I visited the museum.
`->` S + have/has + not + Vpp + for + thời gian = It is + thời gian + since + S + last + V2/ed
44. C. John has played the piano for 10 years.
`->` S + began + Ving + thời gian + ago = S + have/has + Vpp + for + thời gian
45. A I haven't seen her for a week.
`->` The last time + S + V2/ed + was + thời gian + ago = S + have/has + not + Vpp + for + thời gian
46. A. It’s a month since my father last smoked cigarettes.
`->` S + have/has + not + Vpp + for + thời gian = It is + thời gian + since + S + last + V2/ed
47. C. Mr. Brown has had this car for five years.
48. A. It’s years since I enjoyed myself so much.
`->` S + have/has + not + Vpp + for + thời gian = It is + thời gian + since + S + last + V2/ed
49. B We haven’t been to the cinema for a long time.
`->` It is + thời gian + since + S + last + V2/ed = S + have/has + not + Vpp + for + thời gian
50. D I haven’t seen Rose for three years.
D
1. B will be doing
2. A shall have been working
3. B will be taking
4. B will have learned