Điền vào chỗ trống với “for”hoặc “since”. 1. I got here an hour ago. ~ What! You mean you’ve been waiting ………………………………………………………… an hour? 2. I have not seen him …………………………………. he was 16 3. I've known him …………………………………. ages 4. Things have changed a lot…………………………………. our previous meeting. 5. It's been raining…………………………………. four o'clock. 6. I'm sure he's been watching us …………………………………. we came in. 7. He'd been here…………………………………. over an hour when we arrived. 8. I've been trying to fix this computer…………………………………. early this morning. 9. He hasn't had anything to eat…………………………………. nearly a week. 10. It's three years…………………………………. he started learning German. 11. He's been collecting stamps…………………………………. the past twenty years. 12. Nobody has seen him…………….last Friday. 13. It has been foggy…………………………………. some days. 14. He has been fishing…………………………………. six o'clock. 15. They've been living in France …………………………………. eight years. 16. The pilots have been on strike…………………………………. two months. 17. We've had terrible weather…………………………………. Saturday. 18. I've known Tom…………………………………. 1990. 19. We have been waiting for the bus…………………………………. half an hour. 20. She hasn't lost a match…………………………………. April.