Prepositions of Time

Prepositions of time tell us when something happens, how long it lasts, or by when it must be completed. At this level, you need to master not only the basic prepositions (in, on, at, during) but also advanced ones such as by, since, for, until, from...to, between...and, within, before, after, and throughout.

What You'll Learn

How to choose precisely among in, on, at, and during in tricky or overlapping contexts
How to use by, until/till, since, for, from...to, between...and, within, before, after, and throughout to express deadlines, durations, and time ranges
How to avoid common PSLE errors with time prepositions in formal, academic, and narrative writing
How to distinguish between prepositions that appear similar but carry different meanings (e.g., by vs until, since vs for)

When to Use

To state a deadline: "All entries must be submitted by 5 p.m. on Friday."
To express duration from a starting point: "She has lived in Singapore since 2018."
To describe how long something lasts: "The students revised for three hours before the examination."
To indicate a time range: "The library is open from 8 a.m. to 6 p.m."
To show something continues up to a point: "We waited at the bus stop until the rain stopped."

How to Form

Review: In, On, At

You already know the core rules from earlier levels. Here is a summary with advanced examples:

Preposition	Use with	Advanced examples
in	Months, years, centuries	in September, in 2025, in the 21st century
in	Parts of the day	in the morning, in the afternoon, in the evening
in	Seasons / long periods	in the rainy season, in the past decade
in	A period from now (future)	The results will be released in two weeks.
on	Days, dates, specific day-part	on Monday, on 9 August, on the morning of the concert
at	Clock times, mealtimes	at 7.30 a.m., at breakfast, at lunchtime
at	Special time words	at noon, at midnight, at night, at dawn
at	Festivals (the period)	at Christmas, at Chinese New Year

Deadlines and Limits

Preposition	Meaning	Example
by	no later than (a deadline)	Please return the books by Friday.
until/till	continuing up to a point, then stops	The shop remains open until 10 p.m.
before	earlier than a stated time	We arrived before the ceremony began.
after	later than a stated time	The discussion continued after the bell rang.
within	inside a time limit, not exceeding it	The parcel will arrive within three working days.

Durations and Ranges

Preposition	Meaning	Example
for	how long something lasts (a duration)	They practised for two hours every afternoon.
since	from a starting point in the past until now	He has been captain of the team since January.
from...to	marks the start and end of a period	The workshop runs from Monday to Wednesday.
between...and	within two time boundaries	The event will be held between 2 p.m. and 5 p.m.
during	at some point within a period	Several students fell ill during the school camp.
throughout	for the entire duration, from start to finish	The volunteers worked tirelessly throughout the fundraising campaign.

Key Rules

"By" means a deadline; "until" means continuous up to that point: "Submit your essay by Friday" means Friday is the latest you may submit. "You may use the hall until Friday" means you can continue using it right up to Friday, then you must stop. Do not swap them.
"Since" takes a point in time; "for" takes a duration: Use since with a specific moment ("since 2019", "since Monday", "since last July"). Use for with a length of time ("for three days", "for an hour", "for six months"). Never write "since three days" or "for 2019".
"In" can mean "after a period from now": Besides its usual meanings, in can describe a future time span. "The bus will arrive in ten minutes" means ten minutes from now. This is different from "The bus arrived at ten minutes past three", which states a clock time.
"On" overrides "in" when a specific day is named: You say "in the morning" but "on Monday morning". When the part of the day is attached to a named day or date, switch to on. "We have a test on the afternoon of 15 March."
"At" for festivals as a period; "on" for the specific day: Use at when referring to the whole festival period ("at Chinese New Year, we visit our relatives"), but on for the exact date ("The parade is on National Day").
"During" vs "for": During tells you when within a period something happened. For tells you how long it lasted. "She read during the holidays" (when). "She read for two hours" (how long). Do not use during with a number of hours, days, or weeks.
"Throughout" emphasises the full duration: Use throughout to stress that something lasted from start to finish without stopping. "It rained throughout the entire match." If the action happened only at some point during the period, use during instead.

Common Mistakes

Wrong	Right	Why
He has been absent since three days.	He has been absent for three days.	"Since" needs a point in time, not a duration; use "for" with lengths
Please finish the work until 5 p.m.	Please finish the work by 5 p.m.	"By" expresses a deadline; "until" means continuing up to a point
We have a meeting in Monday morning.	We have a meeting on Monday morning.	When a specific day is named, use "on" even with a part of the day
The shop is open during six hours.	The shop is open for six hours.	"During" is followed by a noun phrase, not a quantity of time
She has worked here from 2020.	She has worked here since 2020.	"From" needs a matching "to"; for a past point continuing to now, use "since"
We waited from 3 p.m. until to 5 p.m.	We waited from 3 p.m. to 5 p.m.	Do not combine "until" and "to" -- use one or the other

Clue Words

Deadline prepositions ("by", "before", "within"):

deadline, latest, no later than, must be done, due, submit, hand in, complete

Duration prepositions ("for", "since", "throughout"):

how long, hours, days, weeks, months, years (use for); starting point, a date, a day, a year (use since); the whole, the entire, from start to finish (use throughout)

Range prepositions ("from...to", "between...and", "until/till"):

start and end times, opening and closing hours, a period between two points

Review: "in", "on", "at"

Months and years = in; named days and dates = on; clock times, noon, midnight, night = at

Tip: When choosing between by and until, ask yourself: "Does the action stop at that time, or is it a deadline?" If it is a deadline, choose by. If something continues and then stops at that time, choose until.

Practice Tips

The "since vs for" swap test: Whenever you write since or for, try swapping it with the other word. If the time expression is a specific point (a year, a day, a date), it must be since. If it is a length of time (three weeks, two hours), it must be for. This quick check catches many errors.
The "by vs until" meaning check: Read your sentence aloud. Does the sentence describe a deadline for completing something? Use by. Does it describe an action that keeps going up to that time? Use until. "You may borrow the book until Friday" vs "Return the book by Friday."
The "on + day" override rule: After writing in the morning / afternoon / evening, scan the sentence for a named day or date before or after it. If there is one, change in to on. "We meet in the afternoon" becomes "We meet on Tuesday afternoon."
Highlight and label: In your practice passages, highlight every preposition of time and label it with its function: deadline (by, before, within), duration (for, since, throughout), range (from...to, between...and, until), or point in time (in, on, at). This builds accuracy for the PSLE.

Quick Reference

What you want to say	Preposition	Example
A month, year, or part of the day	in	The concert is in November.
A future span from now	in	The train will depart in five minutes.
A named day, date, or day + part of day	on	The exam is on the morning of 10 October.
An exact clock time, noon, midnight, night	at	Assembly starts at 7.30 a.m.
A festival period	at	We exchange gifts at Christmas.
A deadline (no later than)	by	Submit your form by Wednesday.
Continuing up to a point, then stopping	until / till	Rehearsals will go on until 6 p.m.
Earlier than a stated time	before	Arrive before the gates close.
Later than a stated time	after	We celebrated after the results were announced.
Inside a time limit	within	Reply within 48 hours.
A length of time (how long)	for	We waited for forty minutes.
From a past starting point until now	since	She has played the piano since Primary 3.
A start and end time	from...to	The sale runs from 1 March to 15 March.
Within two time boundaries	between...and	The interview is between 10 a.m. and 12 noon.
At some point within a period	during	He sprained his ankle during the relay race.
For the entire duration	throughout	She maintained her focus throughout the three-hour paper.

Prepositions of Time (P6) (Primary 6)