Use for with a period of time. Examples: for two hours, for six months, for ages

Use since with the start of a period. Examples: since January, since last year, since morning, since 2005

In negative sentences, we can use in instead of for.

Fill in the blanks with for, since or in.

1. She has been working here …………………….. fifteen years.

2. I haven’t met him ………………………. Monday.

3. I haven’t heard anything from him ……………………….. two weeks.

4. We have been waiting ……………………….. ages.

5. I haven’t had a holiday ……………………………. two years.

6. It has been two years ………………………… I left college.

7. It has been ages ……………………… we went to a concert.

8. I haven’t been to a concert ………………………….. ages.

9. She has been here ………………………… morning.

10. She has been jobless ………………………. she left school.

11. I have been waiting here ………………………. a long time.

12. People have made war …………………………..the dawn of civilization.

Answers

1. for, 2. since, 3. for, 4. for, 5. in / for, 6. since, 7. since, 8. for/in, 9. since, 10. since, 11. for, 12. since

The words since and for can also be used as conjunctions. Since is a subordinating conjunction. It can show time or reason.

• She has been jobless since she left university.
• Since he was dishonest, he lost his job.

For is a coordinating conjunction.

• We cancelled the trip for the weather was not good.

Note that it is more common to use because instead of for in this sentence.

• We cancelled the trip because the weather was not good.