This document discusses the use of prepositions to indicate time in English. The preposition "at" is used to refer to specific hours, meals, holidays, and weekends. The preposition "on" is used to refer to days, particular dates, and days combined with parts of the day. The preposition "in" is used to refer to minutes, hours, months, years, seasons, and centuries. It also lists prepositional and non-prepositional phrases to refer to parts of the day.

1. AT/IN/ON
PREPOSITIONS OF TIME

2. TIME: AT
• HOURS: At 2 PM
• MEALS: At lunchtime – at breakfast
• Holidays: At Christmas – At Easter – At New Year
• Weekend: At the weekend
Note: AmE ‘on the weekend’

3. TIME: ON
• DAYS: On Thursday
• A PARTICULAR DAY: On July 1st
On December 31st 1966
On New Year’s Day
On Fiestas Patrias (Independence Day)
• DAY + PART OF THE DAY:
On Monday morning
On Friday night

4. TIME: IN
• MINUTES/HOURS: In 20 minutes
In 2 hours
• MONTHS: In October
• YEARS: In 1981
• SEASONS: In (the) spring/summer/fall/winter
• CENTURIES: In the 21st century

5. PARTS OF THE DAY
IN THE MORNING
IN THE AFTERNOON
IN THE EVENING
AT NOON/MIDDAY
AT NIGHT
AT MIDNIGHT
AT DAWN
NOT PREPOSITION:
TODAY/TOMORROW/YESTERDAY