1. It's 5 years since my father has been to Hanoi.
2. My father has read newspaper for 2 hours.
3. I haven't written her for four years.
4. I've studied English since I was 10 years old.
5. Before I went to school, l went over my lesson
6. After he had done all his exercises, he watched TV.
7. I've never met such a generous person.
8. When did they buy the house?
9. This is the most interesting novel I've read.
10. How long is it since you collected stamps?