may

> can and may
can and may both mean in one of their senses "to be permitted". In this sense can is much less formal than may and is best restricted to informal contexts, as in ""Can I go to the park now?" asked the child". May is used in more formal contexts, as in "May I please have your name?" Both can and may have other meanings. Can has the meaning "to be able", as in "They thought his legs were permanently damaged but he can still walk". May has the additional meaning "to be likely", as in "You may well be right".
The past tense of can is could, as in "The children asked if they could (= be permitted to) go to the park". "The old man could (= be unable to) not walk upstairs". The past tense of may is might, as in "The child asked if he might have a piece of cake (= be permitted to)". "They might (= be likely to) well get here tonight".