• at for a precise time
  • in for months, years, centuries, long periods
  • on for days and dates


*On is frequently omitted before the expressions Thuesday morning, Thuesday afternoon, etc.

  • I saw her on Xmas day.
  • He started work on Monday.


*In some varieties of English people say on the weekend and on Christmas.

  • She often goes out at night.
  • I have a meeting at 10am.
  • I don't usually work at the weekend.
  • I stay with my family at Christmas.
  • We finished the test at the same time.


  1. at a time: He went down the steps two at a time.
  2. at last: At last, they found the answer to the question.
  3. at times: At times, she enjoys a good historical novel.
  4. in case of: In case of rain, the people will stay at home.
  5. in the beginning In the beginning, they didn't understand English.
  6. in the end: In the end, the two policemen caught the thief.
  7. in time for: I came in time for the second half of the movie.
  8. on occasion: On occasion, I enjoy a good television program.
  9. on time: He almost always gets to work on time.
  10. on the spur of the moment: We decided on the spur of the moment.

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