at · on · in
| Prep | Use with | Examples |
|---|---|---|
| AT | Specific clock times · parts of day (night/noon) · fixed expressions | at 7:30 · at midnight · at Christmas · at the weekend (BrE) |
| ON | Days of the week · specific dates · special days | on Monday · on 5 July · on my birthday · on New Year's Day |
| IN | Months · years · seasons · centuries · parts of day (morning/afternoon/evening) | in January · in 2024 · in summer · in the morning |
Memory trick — "clock zoom":
at = a clock point (very specific) → on = a named day → in = a large period (month / year / season). The smaller the unit, the smaller the preposition… until you reach a clock time: use at.
for · since · during · until · by
| Prep | Use | Example |
|---|---|---|
| FOR | Duration — how long | I waited for two hours. · She lived there for a year. |
| SINCE | Starting point (to now) — used with Present Perfect | I've lived here since 2019. · She hasn't eaten since morning. |
| DURING | Within a period of time | I fell asleep during the film. · It rained during the night. |
| UNTIL / TILL | Up to a point in time | I worked until midnight. · Wait till I come back. |
| BY | No later than (deadline) | Please finish by Friday. · I'll be home by 6 pm. |
Exercises
Choose the correct preposition.
1. The party is ___ Saturday evening.
2. The meeting starts ___ 9 o'clock.
3. She was born ___ 1998.
4. I've known her ___ three years.
5. Please send me the report ___ Monday. (= deadline)