Rule 1. ‘May' as a Modal is used to seek permission or grant permission in a formal manner.
Rule 2. ‘May' as a Modal is used to express a possibility, but it is not a certainty, though it is more on the positive side.
Rule 3. ‘May' s a Modal is used to express a wish or prayer.
Rule 4. ‘May' as a Modal is used to express a possibility, whereas ‘might' is used to express a doubt or a possibility more on the negative side.
Rule 5. ‘May' in the Direct Speech is changed into ‘might' in the Indirect Speech, when the Reporting Verb is in the Past Tense.
Examples of Rule 1.
1.She may take my car.
2.May I go round your house?
3.They may do their worst.
4.May I see your new camera?
Examples of Rule 2.
1.I may go to Delhi next month.
2.The guest may arrive in the evening.
3.He may win a lottery prize.
4.You may get a letter tomorrow.
Examples of Rule 3.
1.May you rise in life!
2.May she live long!
3.May you prosper, my son!
4.May God bless you with a son!
Examples of Rule 4.
1.He might be ruined in the business.
2.The patient might die any moment.
3.You might be dismissed.
4.We may win many new friends.
5.He might not come to see you.
6.They may win the war.
Examples of Rule 5.
1.Direct Speech : He said, “ Mohan may come to see me any time."
Indirect Speech : He said that Mohan might come to see me any time.
2.Direct Speech : The people shouted' “May our king live long."
Indirect Speech : The people shouted and prayed that their king might live long.