Since или for. Урок английского языка

1. You haven't smoked sincefor two months.

2. We've been friends with Fred sincefor decades.

3. I haven't worked sincefor a mounth.

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

5. I've read two books sincefor the weekend.

6. They have been ill sincefor Monday.

7. Jane has worked here sincefor two weeks already.

8. He's been working in the field sincefor early this morning.

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

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