Preposition in, or, at

The prepositions in, on, and at can be used to indicate time and place. Notice how they are used in the following situations:

We use:

• At  for a PRECISE TIME
• In  for MONTHS, YEARS, CENTURIES and LONG PERIODS
• On  for DAYS and DATES

Look at these examples :

• I have a meeting at 9am.
• The shop closes at midnight.
• Jane went home at lunchtime.
• In England, it often snows in December.
• Do you think we will go to Jupiter in the future?
• There should be a lot of progress in the next century.
• Do you work on Mondays?
• Her birthday is on 20 November.
• Where will you be on New Year’s Day?

Notice the use of the preposition of time at in the following standard expressions:

Expression	Example
at night	The stars shine at night.
at the weekend	I don’t usually work at the weekend.
at Christmas/Easter	I stay with my family at Christmas.
at the same time	We finished the test at the same time.
at present	He’s not home at present. Try later.

Notice the use of the prepositions of time in and on in these common expressions :

in	On
in the morning	on Tuesday morning
in the mornings	on Saturday mornings
in the afternoon(s)	on Sunday afternoons
in the evening(s)	on Monday evening

When we say last, next, every, this we do not also use at, in, on. :

• I went to London last June. (not in last June)
• He’s coming back next Tuesday. (not on next Tuesday)
• I go home every Easter. (not at every Easter)
• We’ll call you this evening. (not in this evening)

Sample sentences :

I met my wife at the theater. (while watching a movie) I spilled my drink in the theater (on the floor of the building) She works at the library on Wednesdays. She found a rare coin in the library (building). Dr. Jones works at the hospital every day. John was in the hospital for a week with a broken leg.

For school, prison, and church, the is used to indicate the building. No article indicates
the general situation. Note the following:

"practice"/situation	building
in school (studying, listening to teacher, etc.)	in the school (building)
in jail/prison (staying there as a criminal)	in the jail/prison (temporary)
in church (praying, listening to a sermon, etc.)	in the church (building)