Since или for. Урок английского языка

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

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

3. You have been watching TV sincefor hours.

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

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

6. I haven't talked to him sincefor last week.

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

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. They've been in love sincefor three weeks.