Since или for. Урок английского языка

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

2. You haven't smoked sincefor two months.

3. I haven't slept sincefor 48 hours.

4. They haven't visited us sincefor Christmas.

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

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

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

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. New ideas have been put into practice sincefor he was elected our leader.