Since или for. Урок английского языка

1. You haven't smoked sincefor two months.

2. I haven't met Jill sincefor the end of the school.

3. My boss has been away sincefor half a day only.

4. We've been together only sincefor a few days.

5. They haven't visited us sincefor Christmas.

6. She has been in hospital sincefor Monday.

7. These cherry trees have bloomed every spring sincefor 1980.

8. John and Bob have been working on this project sincefor five months already.

9. He worked at that company sincefor ten years before he retired.

10. New ideas have been put into practice sincefor he was elected our leader.