Choose the correct prepositions of time: at, in, on.

1. I love to go swimming at the beach ... summer.
2. What time do your children usually go to bed ... night?
3. Next year, we plan to travel to Taiwan ... September.
4. My birthday is next week. I was born ... October 15th.
5. My grandfather is very old. He was born ... 1939.
6. I am going to meet my friends ... Friday evening.
7. Most stores and businesses are closed ... New year`s Day.
8. I always get up very early ... the morning.
9. My father goes to work ... weekdays, from Monday to Friday.
10. After I eat dinner, I like to watch TV ... the evening.
11. My first class at college begins ... eight o`clock.
12. Last night, I heard a very strange sound ... midnight.
13. My summer holiday starts ... June.
14. He changed his job three times ... the 1990s.
15. My friend wants to have a party ... his birthday.