Fill in for or since into the gaps

For or Since - Exercise 2(Đây là đề bài,điền for hoặc since vào chỗ chấm)
Fill in for or since into the gaps.
1. Nobody has seen him...........  last Friday.
2. It has been foggy ......... some days.
3. He has been fishing ......... six o'clock.
4. They've been living in France..............  eight years.
5. The pilots have been on strike.............  two months.
6. We've had terrible weather ............. Saturday.
7. I've known Tom............  1990.
8. We have been waiting for the bus........ half an hour.
9. She hasn't lost a match............. April.
10. Things have changed...........  she's become headmaster.
11. The police have been looking for him..........  a month.
12. Our dog has been ill ................ two days.
13. I've been looking for this book............  a long time.
14. I've been working ..........I got up.
15. The kettle has been boiling.............  ten minutes.