Dưới đây là các câu hoàn chỉnh dựa trên thông tin đã cho:

8. We have collected stamps since we were children.
9. These students have learned English for five years.
10. Liz has not sent us any letters since she moved to the USA.
11. He has a cold since last Sunday.
12. We have not had holidays for two years.
13. They have already finished their work.
14. She has never been to Cambodia before.
15. I have eaten this kind of food twice.
16. My father has just gone out with his friends.
17. So far, there have been three accidents in our street.
18. Have they walked along the River Thames yet?