 Motil auxiliary verbs. Motil verbs are helping verbs expressing the degree of possibility, ability, permission, or obligation. Let's take a look at modal auxiliary verbs with their uses and examples below. Motil verbs are auxiliary or helping verbs. These kinds of verbs cannot be used on their own, and appear in connection with a main verb. The most common modal verbs are can, could, may, might, shall, should, will, would, must, ought to. Motil verbs affect the main verb they are associated with by expressing the level of possibility, ability, permission and obligation for that action or state. Motil auxiliary verbs also act differently to other verbs. For example, they never change their form, regardless of whether in the singular or plural persons, or whether expressing the past, present, or future.