III,
1. different
2. between
3. out
4. well
5. downstairs
6. written
7. has lived
8. as cold as
9. to study
10. taking
11. have to
12. between
13. himself
14. How long
15. on
IV,
1. My family used to visit Sa Pa last summer vacation.
2. They used to go to school by bus last year.
3. Na isn’t as beautiful as Trang.
4. French is more difficult than English.
5. They have lived here for 10 years.
6. She enjoys swimming and outdoor activities.