Exercise on »since« and »for«

since - if the starting point is given (two o'clock, last Friday, 1998)
- for - if the period of time is given (twenty minutes, two days, one year)

Decide whether to use »since« or »for«.

1. I have been waiting ……….. 4 o'clock.
2. Sue has only been waiting…………. 20 minutes.
3. Tim and Tina have been learning English……….. six years.
4. Fred and Frida have been learning French ………….1998.
5. Joe and Josephine have been going out together ……….. Valentine's Day.
6. I haven't been on holiday ………..  last July.
7. Mary has been saving her money ………..  many years.
8. I haven't eaten anything …………..  breakfast.
9. You have been watching TV   …………….  hours.
10. We have been living here   …………….  2 months.