Prepositions of time: at, in, on
At
at with times of day, including mealtimes, bedtime, etc.
at 3 o’clock, at 10.30am, at noon, at dinnertime, at bedtime, at sunrise, at sunset, at the moment
Also, use at in the following common expressions:
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/at the moment: He’s not home at present.
at night: It was cold at night.
Also, use at in the following common expressions:
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/at the moment: He’s not home at present.
In
Use in with months, seasons, years, decades, centuries and long periods of time in general
in May, in the summer, in 1990, in the 1990s, in the 20th century, in the Ice Age, in the past/future
Parts of the day
in the morning
in the afternoon
in the evening
On
Use on followed by days and dates:
on Sunday, on Tuesday mornings, on 6 March, on 25 December 2010, on Christmas Day, on Independence Day, on my birthday, on New Year’s Eve
last, next, every and this
When we say last, next, every, this we do not 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)