`Đáp` `án:`

11. They haven't cleaned their room for two weeks.

12. John hasn't had his hair cut for over six months.

13. It's the first time we have eaten this kind of food.

14. I have never seen this film before. 

15. He hasn't gone abroad before. 

16. She has driven for 1 month.

17. We have eaten since it started to rain.

18. I haven't had my hair cut since I left her.

19. She hasn't kissed me for 5 months. 

20. We haven't met for a long time. 

21. He has read book for two months. 

22. They have studied English since they were in grade 3.

23. I haven't been abroad before. 

24. I last met my aunt when I was 10 years old.

25. She hasn't seen her parents for a long time.

26. They haven't written to each other for five years. 

27. He has learnt English since he was in grade 6.

28. I last visited the museum three months ago. 

29. Tom has played the piano for 4 years.

30. I have been cooking for the party for 4 hours. 

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Các công thức đổi HTHT - QKĐ

Loại 1: 

S + has/have + not + V3/ed + for/since + time 

→ S + last + V2/ed 

→ The last time + S+ V2/ed + was + time + ago

→ It is / has been + time + since + S+ (last) + V2/ed 

Loại 2: 

How long + has/have + S+ V3/ed?

→ When + did + S + V1?

→ How long is it + since + S+ V2/ed ?

→ How long ago + did + S + start / begin + to V / Ving? 

Loại 3:

S + has/have + V3/ed + for/since + time 

→ S + started / began + to V / Ving 

→ It is / has been + time + since + S+ V2/ed 

Loại 4: 

S + has/have + not/never + V3/ed + ... before

→ This/It is the first time + S+ has/have+ V3/ed

Loại 5:

When + did + S + last + V1?

→ When + was the last time + S + V2/ed?