We often use for and since with perfect tenses:
- We use for to talk about a period of time: five minutes, two weeks, six years
- We use since to talk about a point in past time: 9 o'clock, 1st January, Monday
|a period of time||a point in past time|
|- - - - - - - - - - - -||- • - - - - - - - - - -|
|a long time||I left school|
|ever||the beginning of time|
Look at these example sentences using for and since with the Present Perfect tense:
- I have been here for twenty minutes.
- I have been here since 9 o'clock.
- John hasn't called for six months.
- John hasn't called since February.
- He has worked in New York for a long time.
- He has worked in New York since he left school.