1. We haven't seen her since Christmas day.
2. This is the first time I have eaten this kind of food.
3. It has rained for an hour.
4. The last time I visited my grandfather was 2 months ago.
5. I began studying/to study English 3 years ago.
6. It's 5 years since my brother last saw his best friend.
7. How long have you learnt English?
8. We have lived here for 15 years.
9. She hasn't visited me for 5 years.
10. I haven't written to my uncle since July.
Giải thích:
+ The last time + S + V-ed + was + time = S + have/has not + Vpp + for/since.
+ S + started/began + V-ing/to V = S + have/has + Vpp + for/since.
+ This is the first time + S + have/has (ever) + Vpp = S + have/has not + Vpp + before.