What is a modal auxiliary verb?
The quick answer is to give a list: the modal auxiliaries are must, may, might, can, could, will, would, shall and should. An auxiliary verb is used with a main verb to form a verb phrase. For instance, in the sentence “She was phoning a friend” the word “phoning” is the main verb and the word “was” is an auxiliary verb. An auxiliary verb usually has a grammatical function.
