15.  Lan didn't write to Mary last month

 16.He stared living in HN when he was 12

17. I didn't meet her a long time ago

18. How long ago did you learn french?

19. When did you buy this car?

20.How long have you listened to classical music?

21.I haven't seen her for 10 years

`15`. Lan didn't write to Maryam a month ago.

`->` Câu nghi vấn thì quá khứ: S + did + not + Vinf

`16`. He started living in Ha Noi when he was 12.

`->` S + started + Ving + when + S2 + V2/ed = S + have/has + Vpp + since + S2 + V2/ed

`17`. I didn't meet her a long time ago. ( giống câu 15 )

`18`. How long ago did you learn French?

`19`. When did you buy this car?

`20`. How long have you listened to classical music?

`21`. I haven't seen her for 10 years.

`->` S + last + V2/ed + thời gian + ago = S + have/has + not + Vpp + for + khoảng thời gian