PE-31: Time Expressions: ago, for, since, by, until
The small words that pin a sentence to a moment: how long, since when, by when — and the for/since pair that decides half the marks in an exam.
PE-31: Time Expressions: ago, for, since, by, until
You know the tenses of the past and the future now. This short lesson gives you the words that fix them in time — and it is the last stop before the Perfect tenses, where two of these words (for and since) become absolutely essential. Learn them properly here and Block C will feel easy.
In this lesson you will learn
- ago — counting backwards from now
- for vs since — how long, and since when
- by vs until — the deadline and the whole period
- during vs while, and in for the future
1. ago — counting back from now
Ago measures backwards from this moment, and it always goes after the period of time. It lives with the Past Simple.
We moved to this city three years ago. I saw him a moment ago.
Biz bu shaharga uch yil oldin koʻchib keldik. Uni bir lahza oldin koʻrdim.
Never ago three years — the number comes first, exactly as in
Uzbek.
2. for vs since — the pair that matters most
for + a length of time
- for two hours
- for three days
- for a long time
- for ages
since + when it started
- since 2020
- since Monday
- since nine o'clock
- since I was a child
The test is simple: if you can answer How long? with it, use for. If it answers Since when? — a date, a day, a clock time, an event — use since.
I waited for twenty minutes. — I have known Jasur since primary school.
Yigirma daqiqa kutdim. — Jasurni boshlangʻich sinfdan beri bilaman.
3. by vs until — deadline or whole period?
Both can be translated with the Uzbek "-gacha", which is exactly why they get mixed up. The difference is what happens during the time.
by = not later than (a deadline)
- Finish the work by Friday.
(Friday is the last possible moment) - I'll be home by ten.
until / till = up to that moment
- I'll wait until Friday.
(the waiting continues all the time) - She slept until ten.
4. during vs while
They mean the same thing, but they are followed by different kinds of words: during + a noun, while + a whole clause (subject + verb).
During the lesson we spoke only English. = While we were in the lesson, we spoke only English.
Dars davomida faqat ingliz tilida gaplashdik.
Never during I was reading — that needs while.
5. Two more you will need
- in + a period = after that much time, from now: The bus leaves in ten minutes.
- from … to / till = the two ends of a period: We study from eight to two.
6. Common mistakes
I have been here since three hours.
I have been here for three hours.
She has worked here for 2019.
She has worked here since 2019.
I met him ago two days.
I met him two days ago.
Please send the letter until Monday.
Please send the letter by Monday.
During I was cooking, the phone rang.
While I was cooking, the phone rang.
Practice
1 for or since: Afsona has studied English ? five years, and ? September she has studied Korean too.
Show answer
for … since. Five years is a length (How long?); September is a starting point (Since when?).
2 by or until: The shop is open ? nine, so buy the bread ? then.
Show answer
until … by. The shop stays open the whole time (until); your shopping must be finished no later than nine (by).
3 Correct it: My grandfather died ago ten years.
Show answer
My grandfather died ten years ago.
Ago always follows the period of time — the same order as Uzbek "oʻn yil oldin".
4 during or while: ___ the film, nobody spoke. ___ we were watching, nobody spoke.
Show answer
During the film … While we were watching.
During takes a noun; while takes a subject and a verb.
5 What is the difference? (a) I'll finish it in an hour. (b) I'll finish it by an hour.
Show answer
(a) is correct = one hour from now. (b) is wrong — by needs a clock time or a day: by five o'clock, by Friday.
Key words — Kalit soʻzlar
- Ago...oldin
- For...davomida
- Since...dan beri
- By...gacha (muddat)
- Until / till...gacha (davom etib)
- During...davomida (ot bilan)
- Deadlineoxirgi muddat
- Perioddavr, muddat
- For agesjuda uzoq vaqtdan beri
- Starting pointboshlanish nuqtasi
🎯 Remember this
- ago comes after the period, with the Past Simple.
- for = how long · since = since when (Uzbek "-dan beri").
- by = a deadline, finish before it · until = the action continues to it.
- during + noun · while + subject and verb.
- in ten minutes = from now · for ten minutes = how long it lasted.