May and Can
Both can and may can be used to talk about possibility. But there is some difference between them. Can is used to talk about theoretical possibility; may is used to talk about factual possibility.
- The road may be blocked due to the procession. (Factual
- Any road can be blocked. (Theoretical possibility - It is
possible to block any road.)
- There may be a strike next week. (It is possible that there
will be a strike next week.)
- Strikes can happen any time. (It is possible for strikes to
happen any time.)
- If you drive carelessly, you may have an accident. (Factual
- Accidents can happen any time. (Theoretical possibility)
When we talk about possibility, could often means the same as may or might.
- You may/might/could be right.
May not and Cannot
May not suggests improbability. Cannot suggests impossibility.
- We may not go camping this summer. (= It is possible that we
may not go camping.)
- We cannot go camping this summer. (= It is not possible for
us to go camping this summer.)
Sections in this article
Modal Auxiliary Verbs
May and Can: differences
Should: other uses
Must and have to: The Difference
Should, Ought and Must: The difference