The three prepositions used to describe time are “at,” “on,” and “in.”
- “At” is used for three things:
- times expressed with numbers, as on a clock
- the words noon, midnight, and night
- expressions like “the current time,” “the present,” and “the moment.
- “On” is used with:
- specific dates
- days of the week
- the expressions “weekends,” “the weekend,” and “weekdays”
- “In” is used with:
- some times of day (morning, afternoon, evening, night)
- the phrases “the past,” “the present,” and “the future”
- and a/an quantities of time with a/an (a minute, an hour, a day, a week, a month, a year)
In a typical sentence in English, a prepositional phrase of place comes before a prepositional phrase of time. Prepositional phrases can be placed before the subject in a sentence, or after the verb phrase.