Notes on the usage of prepositions

1. ON
AT
IN
?

2. At / on / in.
Prepositions of time

3. We use IN with:
• Parts of the day: in the morning, in the
evening… ( * at night)
• Months: in January, in March…
• Seasons: in summer, in winter…
• Years: in 1900, in 1644…
• Decades: in the 1960’s
• Centuries: in the 20th century

4. We use ON with:
• Day of the week: on Monday, on Saturday…
• Dates: on 20th May ; on May 20th…
• Particular days: On New Year’s Day, on my
birthday, on the following day, on Christmas
Day ( * at Christmas )

5. We use AT with:
• Clock time: at 5 o’clock; at 7.45 p.m.; at 6.30
a.m.; at 4.15 p.m.; at midday; at midnight
• Night: at night…
• Holiday periods: at Christmas, at Easter, at the
weekend….