How to use FOR and Since.

For and since

We can use the present perfect with for and since.

Vicky has only had that camera for three days.

Those people have been at the hotel since Friday.

I’ve felt really tired for a whole week now.

We’ve lived in Oxford since 1992. NOT We live-here-since-1992. Here something began in the past and has lasted up to the present time.

We use for to say how long this period is {for three days).

We use since to say when the period began (since Friday).

We use how long in questions. How long has Vicky had that camera? ~ Since Thursday, I think.

How long have Trevor and Laura been married? ~ Oh, for about three years.

We can also use the present perfect with for and since when something has stopped happening. / haven’t seen Rachel for ages. She hasn’t visited us since July.