may, might Both words suggest possibility. One meaning of may suggests a likelihood that something will happen. It may rain. Might suggests a remote possibility or a possibility that once existed but no longer does: I might as well be the man in the moon. I might have married her if our circumstances had been different. Consider using might if using may could imply permission instead of possibility: The graduating seniors might skip classes on Friday.
can, could Use can to express certainty or willingness in being able to do something. Use could when there's less certainty or when doing something depends on something else.
can, may Commonly confused. Use can when writing about capability, physical or mental ability, or the power to do something. Use may when writing about authorization or permission and sometimes possibility: They can finish the report by November. May we have an extra month to finish the report? You may lead the horse to water, but you can't make it drink. May is almost always the correct word to use in a question.
could of, may of, might of, must of, should of, would of Frequent misspellings of could have or could've, may have, might have or might've, must have, should have or should've, and would have or would've. Also, avoid using those awkward contractions in writing.Prompting my blog post today is a recent entry in the OxfordWords.blog of OxfordDictionaries.com: May or might: what’s the difference?