III. Fill in the blanks with “since” or “for”: 

1. It has been raining ................................... lunchtime. 

2. My boss will go away ................................... the next ten days. 

3. I'm staying in England ................................... a year. 

4. She has lived in London ................................... 1985. 

5. Please hurry up! We have been waiting ................................... an hour.

6. I have known her ................................... January. 

7. Nam's father has worked in this company ................................... 20 years. 

8. Have you learned English ................................... a long time? 

9. I haven't seen Tom ................................... we left school. 

10. The house is very dirty. We haven't cleaned it ................................... years. 

11. My sister has been a student ................................... two years. 

12. We've lived here ................................... 1990. 

13. I haven't seen Linh ................................... my birthday party. 

14. She has been away ................................... a year. 

15. We've already waited ................................... five days. 

16. They haven't had any rain ................................... very long time. 

17. That buildings has been there ................................... the 19th century. 

18. I have known them ................................... many years. 

19. They have only been there ................................... a few minutes. 

20. My brother works for a company called FPT. He has worked for them ................................... he  graduated from university.