21. How long is it since you saw Tom?

22. It is over a year since I was able to see them.

23. We haven't seen her since Christmas Day.

24. This is the first time I have eaten this kind of food.

25. The last time we visited my grandparents was two months ago.

26. I began studying English three years ago.

27. It's nearly five years since my brother saw his best friend.

28. We haven't seen Tom for nearly two years.

29. I haven't seen him since 1985.

30. The last time I saw each other was over two years ago.

Giải thích:

* Cách viết lại câu của thì Hiện tại hoàn thành.

1. (21)

When did + S + Vnt + O?

⇒ How long is it since + S + Vqk + O?

⇒ How long have/has + S + Vpll + O?

2. (22, 27, 28)

It's + time + since + S + (last) Vqk + O.

⇒ S + have/has + not + Vpll + O + for + time.

3. (23, 25, 29, 30)

The last time + S + Vqk + O + was + time + ago.

⇒ S + have/has + not + Vpll + O + for/ since + time.

4. (24)

This/ It + is the first time + S + have/has + Vpll + O.

⇒ S + have/has + not/never + Vpll + O + before.

5. (26)

S + stopped/began + Ving + O + time + ago.

⇒ S + have/has + not + Vpll + O +for/since + time.

gửi c nha, t xin ctlhn:)