Sure! Here’s a rewritten version of the sentences:

1. Lan has been living in Da Lat for 4 years.
2. My son started learning English when he was young.
3. I have never tried this kind of food before.
4. Lan has never encountered such a beautiful girl before.
5. This is the best book she has read.
6. It is Cuong's first visit to China.
7. My sister has been learning English for 2 years.
8. My parents started drinking when it began to rain.
9. My brother last had his car repaired before I left him.
10. When was the last time he had it done?
11. I haven't seen my grandmother in 6 months.
12. Tonny hasn't bathed since Monday.
13. The last time Tom visited his hometown was 5 years ago.
14. Tom has not returned since.
15. It has been 3 years since we first visited Japan.
16. I had my hair cut in June.
17. The last time we met was 3 years ago.
18. It has been a long time since we last contacted each other.
19. When did you score 10 points in Math?