Since или for. Урок английского языка

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

2. I haven't slept sincefor 48 hours.

3. We haven't seen Mary sincefor the party.

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

5. She has been in hospital sincefor Monday.

6. They have been ill sincefor Monday.

7. Dinosaurs have been extinct sincefor over 60 million years.

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.