A preposition is a word that show the relationship between a noun or a pronoun and some other word in the sentence.
PREPOSITIONS OF TIME
- IN (for MONTHS, YEARS, CENTURIES and LONG PERIODS)
in + the past, the present, the future
e.g.: Do you think we will go to Mars in the future?
in + the morning, the afternoon, the evening
e.g.: I take a walk in the mornings
in + a month, a year, a century, a season
e.g.: Reservations should be made at least one week ahead in summer
- ON (for days and dates)
on + a date
e.g.: I met my boyfriend on November 23th 2019
on + a weekday
e.g.: I go to the gym on tuesdays
on + weekday morning(s), afternoon(s), evening(s)
e.g.: I go to the market on Saturday mornings
- AT (for a precise time)
at + noon, night, midnight
e.g.: You can walk around this city at midnight and be safe.
at + (specific time)
e.g.: I meet you there at 5 o´clock.
at + present, the present time, the moment
e.g.: Mary is busy at the moment, can you call her back later?