May is usually followed by an infinitive without ‘to’: It may rain.
Sometimes may is used without a following infinitive: I’d like to make one or two comments, if I may.
May does not change its form, so the third person singular form does not end in ‘-s’: He may arrive this afternoon.
Questions and negatives are formed without ‘do’: May I make a suggestion?She may not understand.
The negative form may not is sometimes shortened to mayn’t by British speakers of English, but it is not common.
May has no participles and no infinitive form.
There is no past tense, but may have followed by a past participle can be used for talking about past possibilities: She may have changed her mind and decided not to come. When indirect speech is introduced by a verb in the past tense, might is used as the past tense of may: I asked if I might see the paintings.
There is no future tense, but may is used for talking about future possibilities: I may go to London next week.