Modal verbs are auxiliary verbs (also called helping verbs) like can, will, could, shall, must, would, might, and should. After a modal verb, the root form of a verb is generally used. The word to should not appear after a modal verb.

What are the 9 modal auxiliary verbs?

There are nine modal auxiliary verbs: shall, should, can, could, will, would, may, must, might.

What are the 13 auxiliary verbs?

be, can, could, dare, do, have, may, might, must, need, ought, shall, should, will, would. The status of dare (not), need (not), and ought (to) is debatable and the use of these verbs as auxiliaries can vary across dialects of English. If the negative forms can't, don't, won't, etc.