for since ago
for and since
We use for and since to say how long:
We use since + the start of the period ( Monday/ 9 o`clock etc.):
- Barry has been in Canada since January. (= from January to now)
- Barry has been in Canada for six months. ( not since six months)
- I`ve known her since 1980. (= from 1980 to now)
- I`ve known her for a long time. ( not since a long time)
ago = before now:
- Susan started her new job two weeks ago. (= two weeks before now)
- "When did Tom go out?" " Ten minutes ago." (= ten minutes before now)
- I had dinner an hour ago. (= an hour before now)
- Life was very different a hundred years ago.
We use ago with the Past Simple ( did/ had/ started etc.)
Compare ago and for:
- When did she arrive in London?
- She arrived in London four days ago.
- How long has she been in London?
- She has been in London for four days.