The prepositions "at," "in" and "on" can be confusing for English learners. Their meaning is so close that it is sometimes hard to tell when to use each word!
Here are some guidelines to help you decide on the correct preposition to use:
1) When you want to speak about a precise time, use "at."
- The movie starts at nine o'clock.
- They arrived at 6 PM.
- The meeting is at 4:30 this afternoon.
2) When you want to speak about long periods of time (such as months, seasons, years, etc.), use "in."
3) When you want to speak about a particular day, use "on."
- She will be back on Thursday.
- I was born on January 2nd.
- They will join us on Thanksgiving.