Question

what is modal auxiliary​

Answer 1

A modal verb is a type of verb that is used to indicate modality – that is: likelihood, ability, permission, request, capacity, suggestions, order and obligation, and advice etc. They always take base form of verb with them. Examples include the English verbs can/could, may/might, must, will/would and shall/should. 

Answer 2

Auxiliaries, Modals and Main verbs

be, have and do can be auxiliaries and main verbs. They have grammatical functions and are used for forming tenses, questions, the passive, etc.

Modals are can, could, may, might, must, ought to, shall, should, will, would and need (need can also be a main verb).

Examples:

We can play football.

We could play football.

We may play football.

We might play football.

We must play football.

We mustn't play football.

We needn't play football.

We ought to play football.

We shall play football.

We should play football.

We will play football.

We would play football.