FOR

We use for when we are talking about the duration of an action or state, i.e. how long something takes:

I have lived in London for seven years. (This tells us how long I have lived in London.)

For is a preposition here. Although generally used with the present perfect tense, for is also used with other tenses.

SINCE

We use since when we are talking about the time the action or state started:

I have lived in London since 1997. (This tells us when I started living in London.)

Since can be a preposition (since five o'clock) or a conjunction (since I met her). Since is usually used with the present perfect tenses.

AGO

Ago is used to say when past events happened, going back from today to the past:

I came to Japan seven years ago.
I passed my driving test two months ago.

Ago is an adverb and is used with the past tense.

 
Menu