When to use CAN/COULD and MAY

source: Englishing       2018年1月7日
What is a modal verb ? It’s an auxiliary verb used to talk about possibility, ability, permission, requests, offers and so on.
By themselves they don’t mean anything. You always need a main verb to portray their meaning. In this lesson Marc talks about the difference among CAN, COULD and MAY. He goes over four main characteristics: capability, ability, prohibition and permission.
This lesson is intended for intermediate students who wish to improve their English grammar, and for those above levels who wish to clear up doubts about this topic.