1. I last met him two weeks ago.
→ I haven't met him for two weeks.
2. The last time he wrote to me was in September.
→ He hasn't written to me since September.
3. How long is it since you last saw Mary?
→ When did you last saw Mary?
4. When did you start to listen to classical music?
→ How long have you listened to classical music?
5. They provided food then cleaned up the debris.
→ After they had provided food, they cleaned up the debris.
6. He might become the next space tourist in the future.
→ He will be the next space tourist in the future.
7. It's Tony's 15th birthday next week.
→ Tony will be 15 years old next week.
8. I often went fishing on the weekend when I lived on the farm.
→ I used to go fishing on the weekend when I lived on the farm.
9. My family usually stayed with our grandparents in the countryside.
→ My family used to stay with our grandparents in the countryside.
10. Riding your bike fast is dangerous.
→ It is dangerous to ride your bike fast.
11. Watching the circus on television is funny.
→ It is funny to watch the circus on television.
12. Thu is happy. She wins the competition again. (to)
→ Thu is happy to win the competition again.

1. met him for two weeks

2. written to me since September

3. did you last saw Mary

4. have you listened to classical music

5. had provided food, they cleaned up the debris

6. the next space tourist in the future

7. be 15 years old next week

8. to go fishing on the weekend when I lived on the farm

9. to stay with our grandparents in the countryside

10. dangerous to ride your bike fast

11. funny to watch the circus on television

12. happy to win the competition again