Prepositions of Time: at, in, on
We use:
at for a PRECISE TIME
in for MONTHS, YEARS, CENTURIES and LONG PERIODS
on for DAYS and DATES
at
PRECISE TIME
in
MONTHS, YEARS, CENTURIES and LONG PERIODS
on
DAYS and DATES
at 3 o'clock
in May
on Sunday
at 10.30am
in summer
on Tuesdays
at noon
in the summer
on 6 March
at dinnertime
in 1990
on 25 Dec. 2010
at bedtime
in the 1990s