Prepositions of Time — English Grammar Exercises
at, on, in, for, since, during, until, by — every time preposition in one place
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At, on, in for time
The three core time prepositions follow a "zoom" rule: at for precise points, on for days, in for longer periods.
| Preposition | Use for | Examples |
|---|---|---|
| at | clock times, festivals, night, mealtimes | at 9 o'clock, at Christmas, at night, at dinner |
| on | days and dates | on Monday, on 5 June, on New Year's Day |
| in | months, years, seasons, centuries, parts of the day | in July, in 2020, in summer, in the morning |
✅ The meeting starts at 9 o'clock.
✅ We have a test on Monday.
✅ Her birthday is in July.
Watch out: it's at night but in the morning / afternoon / evening. Use on for a specific day's part: on Monday morning.
For and Since
- for + a period of time (how long): for two hours, for three years
- since + a point in time (the starting moment): since 2015, since Monday
✅ We waited for two hours.
✅ She has lived here since 2015.
During and While
- during + a noun: during the film, during the summer
- while + a clause (subject + verb): while I was watching the film
Until and By
| until | up to a point, continuously — something keeps happening |
| by | at or before a deadline — a single action happens before then |
✅ The shop is open until midnight. (open continuously)
✅ Please finish the report by Friday. (the deadline)
In and Ago
- in + a period = the future, counting forward from now: The train leaves in ten minutes.
- ago = the past, counting back from now: They left three years ago.
Common mistakes
| ❌ | ✅ |
|---|---|
| The test is at Monday. | The test is on Monday. |
| The meeting is in 9 o'clock. | The meeting is at 9 o'clock. |
| I've known her since two years. | I've known her for two years. |
| He slept during I was talking. | He slept while I was talking. |
| Finish it until Friday. | Finish it by Friday. |
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The meeting starts ___ 9 o'clock.
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at
Use 'at' for clock times — at 9 o'clock, at noon, at midnight.
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We have an English test ___ Monday.
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on
Use 'on' for days of the week — on Monday, on Friday.
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Her birthday is ___ July.
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in
Use 'in' for months — in July, in December.
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The school first opened ___ 2010.
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in
Use 'in' for years — in 2010, in 1999.
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I always feel sleepy ___ the afternoon.
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in
Use 'in' for parts of the day — in the morning, in the afternoon, in the evening.
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The streets are very quiet ___ night.
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at
'At night' is a fixed expression — not 'in the night' in everyday use.
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The wedding is ___ the 5th of June.
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on
Use 'on' for specific dates — on the 5th of June, on 1 January.
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We waited ___ two hours, but the bus never came.
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for
Use 'for' with a period of time — for two hours, for a week.
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She has lived in this city ___ 2015.
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since
Use 'since' with a point in time — the moment something started. Since 2015, since Monday.
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He fell asleep ___ the film.
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during
Use 'during' before a noun — during the film. 'While' needs a clause (while he was watching).
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The supermarket stays open ___ midnight.
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until
Use 'until' for something that continues up to a point in time.
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Please send me the report ___ Friday at the latest.
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by
Use 'by' for a deadline — the action must be completed at or before that time.
Prepositions of Time: Complete Grammar Reference
Time prepositions are one of the most frequently tested areas in English grammar exams — and one of the most error-prone for learners at B1–B2 level. Analysis from the Cambridge Learner Corpus shows that preposition errors account for approximately 16% of all grammar mistakes in B1–B2 writing samples, with time prepositions responsible for a disproportionate share. The challenge is not a single rule but a network of contrasts: at/on/in for points and periods, for/since for duration versus starting point, during/while for nouns versus clauses, until/by for continuity versus deadlines, and a set of idiomatic fixed expressions that follow their own logic. The 45 exercises across 3 practice blocks build systematic control across all the key areas.
At, On, In — The Core Contrast
The three general time prepositions follow a scale from precision to breadth. At marks the most precise points: clock times, meal times, and certain fixed expressions. On marks days and dates — the middle level of specificity. In marks the broadest periods: months, seasons, years, and centuries.
I'll see you on Friday. (day of the week)
I was born on 15th March. (specific date)
She started university in September. (month)
We always go skiing in winter. (season)
The project was completed in 2024. (year)
Fixed expressions follow set patterns regardless of the scale: at night, at the weekend, at noon, at midnight, in the morning, in the afternoon, in the evening, on Monday morning. Note that 'in the morning/afternoon/evening' shifts to 'on' when a specific day is added: 'on Monday morning'.
For and Since — Duration vs Starting Point
For and since both connect the past to the present, but they answer different questions. For answers 'how long?' with a period of time. Since answers 'from when?' with a starting point.
I've lived in this city since 2018. (starting point: from when)
He's been waiting for over an hour. (duration)
They've known each other since they were children. (starting point — a clause)
An important subtlety: for is not restricted to the present perfect — 'I worked at that company for three years before I quit' is correct past simple. Since, however, almost always requires a perfect tense (present perfect or past perfect), because it inherently implies an unbroken connection to a reference point. Using from in place of since is a very common learner error: 'She has lived here from 2019' is non-standard; the correct form is 'since 2019'.
During and While — Nouns vs Clauses
Both during and while express simultaneity — something happening within the timeframe of something else — but they require different grammatical structures.
Please don't use your phone during the lesson. (during + noun)
She read a book while he was driving. (while + clause)
The phone rang while I was cooking. (while + clause)
The structural test is simple: if the next word is a noun or noun phrase, use during. If the next word is a subject followed by a verb, use while. Mixing the two produces a clear error: 'During she was on holiday...' is wrong — the clause demands while.
Until and By — Continuity vs Deadline
Until and by both point to a moment in the future, but they describe different relationships between an action and that moment.
I'll wait for you until you arrive. (action continues and stops when you arrive)
You need to submit the report by Friday. (deadline — done at some point before Friday)
The project must be completed by the end of the month. (deadline)
A reliable paraphrase test: if you can substitute 'no later than', the preposition is by. If the sentence describes an ongoing state or action that stops at a point, the preposition is until. One of the highest-frequency errors in learner writing is using until for deadlines: 'Please send me the documents until tomorrow' should be 'by tomorrow'.
In, After, Ago — Future Periods and Past Distance
Three expressions handle time measured from the present. In + time period means 'after that amount of time from now' and points forward. Ago + time period counts back from now and always follows the time expression. After in time expressions refers to a sequence — 'after the event' — not to a fixed interval from now.
The train leaves in twenty minutes — we'd better hurry. (from now)
We moved to this city three years ago. (three years back from today)
She graduated from university two years ago. (ago follows the period)
A persistent Russian and Slavic learner error is 'after five minutes' for a future interval counted from the present. English uses 'in five minutes' — after is for sequences ('after the meeting', 'after dinner'), not for fixed intervals from now.
Fixed Time Expressions
Some time phrases are idiomatic and must be learned as whole units. The most tested are the on time / in time and at the end / in the end pairs.
We arrived just in time to catch the train. (= not too late, before the deadline)
At the end of the film, the hero dies. (= the final point of something specific)
In the end, we decided to cancel the trip. (= eventually, after deliberation)
I'm quite busy at the moment — can I call you back? (= right now, fixed expression)
Common Mistakes
✗ I'll call you in Monday morning. → ✓ I'll call you on Monday morning.
✗ She has lived here from 2019. → ✓ She has lived here since 2019.
✗ I haven't eaten anything from this morning. → ✓ I haven't eaten anything since this morning.
✗ During she was on holiday, someone broke in. → ✓ While she was on holiday, someone broke in.
✗ Please send me the documents until tomorrow. → ✓ Please send me the documents by tomorrow.
✗ I'll be ready after five minutes. → ✓ I'll be ready in five minutes.
✗ I'm very busy in the moment. → ✓ I'm very busy at the moment.
✗ I was born in 15th March. → ✓ I was born on 15th March.
✗ I didn't enjoy it at first, but at the end I learned a lot. → ✓ I didn't enjoy it at first, but in the end I learned a lot.
Frequently Asked Questions
What is the difference between at, on, and in for time expressions?
Use 'at' for precise clock times and fixed points: 'at 9 o'clock', 'at midnight', 'at the weekend'. Use 'on' for specific days and dates: 'on Monday', 'on 15th March', 'on Christmas Day'. Use 'in' for longer periods — months, seasons, years, and centuries: 'in September', 'in winter', 'in 2024', 'in the 20th century'. A simple rule: the more specific the time, the shorter the preposition — from 'in' (widest) through 'on' to 'at' (most precise).
What is the difference between 'for' and 'since'?
'For' is followed by a duration — a length of time: 'for three years', 'for ages', 'for six months'. 'Since' is followed by a starting point — the moment when something began: 'since 2019', 'since Monday', 'since we were children'. Both typically appear with the present perfect when the situation is still true now: 'I have lived here for ten years' / 'I have lived here since 2014'. With past simple, only 'for' is possible: 'I worked there for three years (then left)'.
When do I use 'during' and when do I use 'while'?
'During' is a preposition and must be followed by a noun or noun phrase: 'during the lesson', 'during my holiday', 'during the storm'. 'While' is a conjunction and must be followed by a subject and verb (a clause): 'while I was cooking', 'while she slept', 'while he was on holiday'. A quick test: if you can replace the word with 'in the course of' + noun, use 'during'. If you can replace it with 'at the same time as' + clause, use 'while'.
What is the difference between 'until' and 'by'?
'Until' (or 'till') expresses continuous action up to a point in time — the action keeps going and then stops: 'The library is open until 9 pm', 'I'll wait until you arrive'. 'By' expresses a deadline — the action must be completed at or before a point in time: 'Submit the report by Friday', 'The project must be finished by the end of the month'. Test: if you can rephrase with 'no later than', use 'by'. If you can rephrase with 'and then it stops', use 'until'.
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