Complete the sentences with 'at', 'in', or 'on' as appropriate.

Here is the completed exercise: 1. Santa Claus comes **on** Christmas. 2. That shop closes **at** midnight. 3. I have an exam **in** May. 4. We sleep **at** night. 5. They don’t work **on** Fridays. 6. I leave **on** 6th January. 7. I hope you arrive **on** time. 8. We wake up **at** dawn. 9. We’ll meet **at** sunset. 10. He goes to the seaside **in** the summer. 11. Witches fly **on** Halloween night. 12. Rock and roll started **in** the 50’s. 13. I believe people will live on the moon **in** the future. 14. People drink champagne **on** New Year’s Eve. 15. What do we celebrate **on** Easter? 16. I was born **in** 1999. 17. Does she work **on** Sundays? 18. Mrs. Smith waters the flowers **in** the morning. 19. It is very hot here **in** summer. 20. She always goes shopping **on** Friday afternoon. 21. School starts **in** September. 22. He always comes **at** tea time. 23. I hope the weather will be nice **at** the weekend. 24. My father hates driving **at** night but he likes driving **in** the morning. 25. I’ll be with you **in** five minutes. 26. I am tired **at** the end of the day. 27. I ski a lot **in** winter. 28. The plane leaves **at** 9.20 pm. 29. He wakes up **at** 7.30. 30. She’ll be back **in** an hour.