For / Since: Present Perfect Tense'te, ‘How long' sorusunun cevabı olarak kullanılırlar.
for: sürecinin uzunluğunun belirtildiği yerde; since: sürecin başladığı zamanla birlikte kullanılır.

Ex:
since my childhood (beginning) for a long time (period of time)
1. A: How long have you lived in this town?
B: For seven years.
2. A: How long has the doctor been at the hospital?
B: Since the morning.

Complete ‘for' or ‘since'
1. We haven't been to our hometown ………….months.
2. The girl hasn't stopped crying …………… last night.
3. My teacher has asked a lot of questions ……………… the beginning of the lesson.
4. The doctors have worked hard ………….. hours.
5. My friends have written a lot of essays ……… two days.
6. The guests have visited some museums …………. they arrived in İstanbul.
7. My mother has packed five suitcases …………… the morning.

8. She has bought two houses …………. five years.
9. He has worked in his office …………….. a short time.
10. My cousin has played two instruments ………….. she was a little child.
11. I've been here …………………… yesterday night.
12. I've learnt English ……………… 4th class.
13. He has swum everyday …………… his youth.
14. I've admired her ……………… we first met.
15.

He has been a professional coach ……………… ten years.

Answers:

1. for 2. since 3. since 4. for 5. for
6. since 7. since 8. for 9. for 10. since
11. since 12. since 13. since 14. since 15. for