B1–B2

For and Since — English Grammar Exercises

at, on, in, for, since, during, until, by — every time preposition in one place

For and Since — Duration vs Starting Point

The for / since contrast is tightly linked to the present perfect tense and ranks among the top five most tested grammar points in B1–B2 English exams. Cambridge Learner Corpus data shows that since/for confusion appears in approximately 30% of B1–B2 learner texts that contain present perfect sentences. Substituting from for since is a particularly common error for speakers of Slavic languages.

For — How Long

For is followed by a period of time — a length, not a specific moment:

She's been studying English for five years.
He's been waiting for over an hour.
I worked at that company for three years before I quit. (past simple also fine)

Since — From When

Since is followed by a starting point — a specific moment, date, or event:

I've lived in this city since 2018.
We haven't seen each other since the wedding.
They've known each other since they were children. (since + clause is possible)

The 'From' Error

'From' is used in 'from...to' ranges ('from Monday to Friday', 'from 9 to 5'). Using from alone as a starting point is non-standard in present perfect sentences:

✗ She has lived here from 2019. → ✓ She has lived here since 2019.

Common Mistakes

✗ I have known Maria from ten years. → ✓ I have known Maria for ten years.
✗ I haven't eaten anything from this morning. → ✓ I haven't eaten anything since this morning.
✗ She has lived here from 2019. → ✓ She has lived here since 2019.

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'.