Common mistake - can, could or may


Possibility

When we talk about possibility, we use can, could and may, but they are different in meaning:

Permission

We use can, could and may to ask for permission. We use can and may, but not could, to give permission. May is less common:

Requests

When we make requests, we can use can or could (but not may). Could is more polite than can:

Can you call back later? I’m busy now.

Could you call back later? I’m busy now.

Teachers and parents often use can and could in requests:

Can you open you books at page 34, please.

Can you please refrain from chewing gum.

Could you just sit down and listen!

Can, could or may: typical errors

  • Could in the present only expresses weak possibility. Can expresses strong possibility:

I can travel in July because my exams will definitely be finished at the beginning of that month. (strong possibility)

I could travel in July because my exams will probably be finished at the beginning of that month. (weak possibility)

  • We don’t normally use could to talk about general truths which refer to the present time. We use can instead:

Not everyone can afford to buy organic food.

Not: Not everyone could afford …

  • We use could, not can, to express future possibility. Can expresses that we are certain of something:

Working in London next summer could be a great experience. (The speaker thinks this is possible, in particular circumstances)

Not: … can be a great experience.

#Commonmistake #Grammar