may expresses probability if i'm free tomorrow, i may go.(here i'm not sure) i'm free tomorrow, so i'll go to the theatre.(here i'm sure) to express ability in future , use will be able to when i was four, i could ride a bike i can speak english now. i will be able to drive a car when i leave school. i think in the furure people will be able to live on the moon.

No. Use "can" when you mean "can" and use "may" when you mean "may".

Use.... "I will be able to go to the store" si quieres decir "Poderé ir a la tienda/voy a poder a ir a la tienda." o "I may go to the store" si quieres decir "Tal vez iré a la tienda/quizás voy a ir a la tienda."

Hi there, My name is Ut, I am going to Spain at the end of this year, trying to make some good friends there! Thanks for adding me and hope to talk with you soon on Italki or skype: bleuciel204 Take care Ut

May is used for possibility or permission. May I go outside? I may go to the movie if I have the time. Can refers to ability. I can learn English if I study enough. I can ride a bike. Future use for can... I will be able to.... I hope that helps.