1. I last saw him two years ago.
→ I haven't seen him for two years.

2. She began to play volleyball when she was eight.
→ She has played volleyball since she was eight.

3. I have taught English at Nguyen Khuyen school for sixteen years.
→ I started teaching English at Nguyen Khuyen school sixteen years ago.

4. We haven't met each other for three years.
→ It's three years since we met each other.

5. I haven't been to the dentist's for two years.
→ It's been two years since I went to the dentist's.

6. It's three months since she started learning French.
→ She has been learning French for three months.

7. I have never met him here before. (first)
→ It is the first time I have met him here.

8. When did you start learning English?
→ How long have you been learning English?
→ How long ago did you start learning English?

9. When did you last hear from him? (since)
→ How long is it since you last heard from him?

10. She was chosen for the team two years ago.
→ She has been in the team for two years.

11. Nhung will be fifteen next week.
→ It is Nhung's fifteenth birthday next week.