Since, For in Present Perfect Tense

Choose the right words for or since to complete the following English sentences in Present Perfect Tense.
1. We haven't met Christmas.
2. We haven't been in the opera over a year.
3. I haven't spoken German the end of the war.
4. You have kept me waiting half an hour!
5. It is about two years we last had news of him.
6. I haven't bought a new book April.
7. We haven't seen our cousin ages.
8. His wife has changed a lot the last time we met.
9. My daughter hasn't written to me my birthday.
10. We have lived here many years.
11. It hasn't snowed here six months.
12. Our guests have been sailing tea-time.
13. It has been several hours I had dinner.
14. There hasn't been any war in this country over a century.
15. Nothing has been changed here the Middle Ages.