PREPOSITION IN, ON, AT

DefinitionA preposition is a word or groups of words used before a noun or a pronoun to show place, position, time or method. The prepositions in, on, and at can be used to indicate time and place.

Prepositions: In, On, and At (with specific times and places)
The prepositions in, on, and at can be used to indicate time and place. Notice how they are used in the following situations:

Preposition	Time	Place
In	Year, Month, In 1999, In December	Country, State, City In Japan, In Utah, InTaipei
On	Day, Date On Saturday, On May 1	Street On Main Street, On 1st Ave.
At	Time At 8:00, At 7:30	Address At 815 East Main Street

In many languages, there is only one preposition for the above situations. In English there are three. Just remember that in usually indicates the "largest" time or place, and at usually indicates the "smallest" time or place. Examples:

Prepositions with articles and locations

When talking about locations, use at to indicate the general vicinity or area, andin to
indicate inside the building, enclosed area, etc. For example:

at the swimming pool (on site)	in the swimming pool (in the pool itself i.e. in the water)
at the post office/bank (general)	in the post office/bank (inside the building)
at the zoo (visitors, general area)	in the zoo (animals in their cages)
at school	in the classroom

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 articleindicates
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)

We use:
• at for a PRECISE TIME
• in for MONTHS, YEARS, CENTURIES and LONG PERIODS
• on for DAYS and DATES

at
PRECISE TIME

at 3 o’clock
at 10.30am
at noon
at dinnertime
at bedtime
at sunrise
at sunset
at the moment

in
MONTHS, YEARS, CENTURIES and LONG PERIODE

in May
in summer
in the summer
in 1990
in the 1990s
in the next century
in the Ice Age
in the past/future

on
DAYS and DATES

on Sunday
on Tuesdays
on 6 March
on 25 Dec. 2010
on Christmas Day
on Independence Day
on my birthday
on New Year’s Eve

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 the morning
in the mornings
in the afternoon(s)
in the evening(s)

on Tuesday morning
on Saturday mornings
on Sunday afternoons
on Sunday 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)

English Primbon