Prepositions of Time — English Grammar Exercises
Interactive exercises with instant feedback. Practice at, on, in, for, since, during, until, by and more.
Prepositions of Time: Quick Reference
English uses different prepositions depending on whether you're talking about a precise point in time, a day, or a longer period.
At, On, In — The Core System
- at — precise points: at 5 o'clock, at midnight, at noon, at night
- on — days and dates: on Monday, on 15th March, on Christmas Day
- in — longer periods: in September, in 2024, in winter, in the morning
Duration and Starting Points
- for — how long: for three years, for an hour
- since — when it started: since 2020, since Monday
- during — within an event: during the meeting (+ noun)
- while — at the same time: while I was sleeping (+ clause)
Deadlines
- until — action continues up to: wait until 5 pm
- by — must be done before: finish by Friday
Common Mistakes
✗ I've lived here from 2020. → ✓ I've lived here since 2020.
✗ I'll be back after ten minutes. → ✓ I'll be back in ten minutes.
Frequently Asked Questions
When do you use 'at', 'on', and 'in' for time in English?
Use 'at' for precise points in time — at 5 o'clock, at midnight, at noon, at night. Use 'on' for days and dates — on Monday, on 15th March, on Christmas Day. Use 'in' for longer periods — in September, in 2024, in winter, in the morning. The pattern goes from specific to general: at (point) → on (day) → in (period).
What is the difference between 'for' and 'since' in English?
'For' describes duration — how long something lasts: 'for three years', 'for an hour', 'for a long time'. 'Since' marks a starting point — when something began: 'since 2020', 'since Monday', 'since I was a child'. A common mistake is using 'from' instead of 'since' with present perfect: say 'I've lived here since 2020', not 'from 2020'.
What is the difference between 'until' and 'by' in English?
'Until' means an action continues up to a point in time — 'Wait until 5 pm' (keep waiting, then stop at 5). 'By' means something must be completed before a deadline — 'Finish by Friday' (it must be done at some point before Friday). 'Until' is about duration; 'by' is about a deadline.
What is the difference between 'during' and 'while'?
'During' is a preposition followed by a noun — 'during the meeting', 'during lunch'. 'While' is a conjunction followed by a clause (subject + verb) — 'while I was sleeping', 'while she studied'. They often describe the same situation but have different grammar: 'during the film' = 'while we watched the film'.