Помогите,пожалуйста.Вставьте подходящий предлог медли (at, in, on) там, где это

Помогите,пожалуйста.
Воткните подходящий предлог медли (at, in, on) там, где это нужно
1. Dinner is usually ______at_____ 7 oclock.
2. We went to Scotland _________ last summer.
3. We have long holidays _______in____ summer.
4. When have we got Biology? - _________ Friday mornings.
5. There is a school party ___________ 31st January.
6. We are _____________ the 21st century.
7. The game is ____________ 9.45.
8. Is there a party ____________ your brothers birthday?
9. Where was he _____________ the weekend?
10. Where is he ___________ the moment?
11. Your teacher isnt here ___________ present.
12. There are usually a lot of parties _________ New Years Eve.
13. He wasnt there _________ the end of the concert.
14. Where are you usually __________ the evening? And __________ night?
15. Do you get any presents ___________ Christmas Day?
16. He was born ___________ 1999.
17. We usually go there ___________ weekends ___________ spring.
18. He phoned me ____________ Tuesday.
19. We went to bed late ____________ last night.
20. He gets up ___________ 7 oclock ___________ weekdays.
21. She was in hospital ___________ that time.
22. The school party is ___________ June 8th __________ 8 oclock.
23. I'm leaving __________ next Saturday.