Ответ:

Insert on/in/at:

  1. on 10 October
  2. at half past four
  3. in 1987
  4. on Friday morning
  5. in the morning
  6. in summer
  7. on Wednesday
  8. Goodbye! See you Saturday.
  9. I usually get up at 8 o'clock in the morning.
  10. What are you doing on Thursday evening?