Since или for. Урок английского языка

1. I haven't slept sincefor 48 hours.

2. I haven't worked sincefor a mounth.

3. We've been together only sincefor a few days.

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

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

6. Jane has worked here sincefor two weeks already.

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

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