May and Able to

May

May: it we use to express possibility. It can also be used to give or request, permission, although this usage is becoming less common.

Structure:

subject + may + infinitive
Example: You may borrow my car.

BE ABLE TO

We use be able to to express ability. More formal than MAY, We sometimes use "be able to" instead of "can" or "could" for ability. In addition, "can" and "could" have no infinitive form. So we use "be able to" when we want to use other tenses or the infinitive.                                                                                                                               We use be able to:  to talk about ability

Structure of Be able to

subject + be + able + infinitiv
we can use in past, present and future
EXAMPLE:

Ø  I was able to drive

Ø  I will be able to drive

Ø  I have been able to drive