1) Why Are FOR, SINCE and AGO Confusing?

These three words all relate to time, but they answer very different questions. Mixing them up is one of the most common mistakes in English.

FOR → How long? (duration)
SINCE → Since when? (starting point)
AGO → How long ago did it happen? (past moment)

2) The Three Words at a Glance

3) FOR — Expressing Duration

Use FOR to express how long something has lasted or lasted. It is followed by a period of time.

FOR + period of time: for five minutes · for two hours · for a week · for three months · for six years · for a long time

FOR with Present Perfect — ongoing situation:
Aminata has studied English for three years. Aminata étudie l'anglais depuis trois ans.
I have lived in Bouaké for my whole life. J'ai vécu à Bouaké toute ma vie.

FOR with Past Simple — finished situation:
She studied in Abidjan for two years. Elle a étudié à Abidjan pendant deux ans.
He waited at the bus stop for forty minutes. Il a attendu à l'arrêt de bus pendant quarante minutes.

4) SINCE — Expressing a Starting Point

Use SINCE to express when something started. It is followed by a specific point in time. The situation is almost always still happening now → Present Perfect.

SINCE + point in time: since 2018 · since Monday · since March · since last year · since I was born · since the meeting

Konan has worked at this company since 2020. Konan travaille dans cette entreprise depuis 2020.
She has been sick since last Tuesday. Elle est malade depuis mardi dernier.
I haven't seen him since the graduation ceremony. Je ne l'ai pas vu depuis la cérémonie de remise des diplômes.

5) AGO — Referring to a Past Moment

Use AGO to say how long before NOW something happened. It always goes after the time expression and is always used with the Past Simple — never with the Present Perfect.

Time expression + AGO: five minutes ago · two hours ago · a week ago · three years ago · a long time ago

I started learning English two years ago. J'ai commencé à apprendre l'anglais il y a deux ans.
She left the office ten minutes ago. Elle a quitté le bureau il y a dix minutes.
Côte d'Ivoire gained independence many decades ago. La Côte d'Ivoire a obtenu son indépendance il y a plusieurs décennies.

6) Timeline — Seeing the Difference

Example: "I moved to Bouaké 5 years ago and I have lived here for 5 years / since 2019."

7) FOR vs SINCE — Side by Side

She has been a teacher for ten years. / She has been a teacher since 2014. Elle est enseignante depuis dix ans. / Elle est enseignante depuis 2014.

I haven't eaten for six hours. / I haven't eaten since this morning. Je n'ai pas mangé depuis six heures. / Je n'ai pas mangé depuis ce matin.

8) Questions — How Long? / When? / How Long Ago?

9) Real-Life Context — Côte d'Ivoire

💬 Dialogue — Job interview in Abidjan

10) Common Mistakes to Avoid

✘ I have started this job three months ago. → ✔ I started this job three months ago. (Past Simple)
AGO always goes with Past Simple, never Present Perfect.

✘ She has lived here since five years. → ✔ She has lived here for five years.
SINCE + specific point in time. FOR + period/duration.

✘ I know him for a long time. → ✔ I have known him for a long time.
An ongoing situation from the past to now → Present Perfect + FOR.

✘ How long ago have you been here? → ✔ How long have you been here? / How long ago did you arrive?
Never mix AGO with Present Perfect.

✘ He works here since Monday. → ✔ He has worked here since Monday.
SINCE with an ongoing situation → Present Perfect.