Điền cụm từ với " for ", "since" hoặc "ago"
1. The police have been looking for him........a month
2. i've been looking for this book.a long time
3. I've been working......I got up
4. the kettle has been boiling......ten minutes
5. they have been living in Madrid....1972
6. he has been in prison.......four years
7. he has known about the fact........a long time
8. conditions have changed a lot........we were children
9. our teacher has been very ill......the last month
10. i haven't eaten anything.........twenty for hours
11. in fact he always very rude. We have been waiting for him.......half an hour
12. i haven't seen him for three years. It is because i haven't been there......i left school
13. i have been trying to mend this old fashioned car...hours
14. one of my friends has been teaching in tokyo..........three years. i haven't met him since last year
15. i haven't enjoyed myself ....two weeks since i heard thay my final exam grades were low