INTERMEDIATE - GRAMMAR


AGO, FOR AND SINCE

AGO
    We went to Hawaii three years ago.
    I passed my final exam a few weeks ago.

We use ago to talk about something that happened in the past. We always use it with a period of time (a few minutes ago, many years ago, 10 minutes ago). It is used in past simple sentences.

SINCE
    I've been in Africa since May.
    He's been studying French since 1999.

We use since to talk when something started. It is still happening now. We use since with perfect tenses.

FOR
    I've been waiting for a taxi for over 2 hours.
    He has been sick for two months.

We use for to tak about something that has been happening (or happened) for a period of time. We can use it with perfect tenses or past tenses.