in

on

at

no preposition

in the morning/the evening/the afternoon

months (in May)

seasons (in spring)

years (in 2020)

decades (in the 60s)

centuries (in the 20th century)

 

days of the week (on Friday)

days of the week + morning/afternoon/evening (on Monday morning)

dates (on the 15th of May)

particular days (on my birthday, on that day, on Christmas day)

time (at 3 o’clock)

at midday/midnight

word time (at that time, at lunchtime/dinnertime)

at night

at the weekend

festival periods (at Christmas/ Easter)

last/this/next week/month/year

tomorrow morning

one day/summer/year

Exercises