Can & Could
Talking about ability
Can you speak Bengali? (present)
She could play the piano when she was five. (past)
Can you give me a ring at about 10?
Could you speak up a bit please? (slightly more formal, polite or 'softer')
Can I ask you a question?
Could I ask you a personal question? (more formal, polite or indirect)
Reported speechCould is used as the past of can.
He asked me if I could pick him up after work.
You can drive when you're 17. (present)
Women couldn't vote until just after the First World War.
Choice and opportunities
If you want some help with your writing, you can come to classes, or you can get some 1:1 help.
We could go to Stratford tomorrow, but the forecast's not brilliant. (less definite)
Could (NOT can) is sometimes used in the same way as might or may, often indicating something less definite.
When I leave university I might travel around a bit, I might do an MA or I suppose I could even get a job.
I think you could be right you know. (NOT can)
That can't be the right answer, it just doesn't make sense.
If I'd known the lecture had been cancelled, I could have stayed in bed longer.
May & Might
May & might sometimes have virtually the same meaning; they are used to talk about possibilities in the past, present or future. ("Could" is also sometimes used).
May is sometimes a little bit "more sure" (50% chance); whereas might expresses more doubt (maybe only a 30% chance).
Originally Posted by sumansen