Since или for. Урок английского языка

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

2. We've lived here sincefor seventeen years.

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 haven't visited us sincefor Christmas.

7. He hasn't played the piano sincefor he was a boy.

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

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

10. They've been teaching here sincefor quite a long time.