Use "since" or "for" to fill in each blanks
1. ………. the first week of January, the men have worked harder.
2. ………. she graduated from university, she has made a lot of progress on science.
3. I am proud to say that we have changed working conditions ………. two years.
4. Our country has changed better ………. he was in charge of President.
5. The manager has exchanged his idea with the warehouse workers ………. she came here.
6. The children have played with their dolls ………. fifteen minutes.
7. You have been our loyal client ………. we operated in 2005.
8. Lan and Quang have close friends ………. they studied in Ho Chi Minh City.
9. His health has been worse ………. he came back from hospital.
10. They have played football in the yard ………. four o’clock.
11. We have left for New York ………. five days.
12. The developing countries have tried their best to overcome the incident ………. years.
13. Unfortunately, we have got lost in the city ………. we got off bus.
14. ………. I passed the final examination, my friends have approached and congratulated me.