Since или for. Урок английского языка

1. Jane hasn't been to America sincefor 1981.

2. I haven't slept sincefor 48 hours.

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

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

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

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

7. Jane has worked here sincefor two weeks already.

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

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

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