When to Use Can and Could?

Auxiliaries are the helping verbs that help the action verbs to make tenses and passive forms. There are two types of Auxilieries- Primary Auxiliaries and Modal Auxiliaries.

Primary Auxiliearies include examples like am, is , are, was, were, do, does, did, have, has, had etc.

Modal Auxiliaries, also called Modals are Shall, should, will, would, can , could , may, might, must and ought to.