A student writes:
<< Dear Dr. Vicars,
Are WILL, CAN, and SHOULD auxiliary verbs or model verbs?
Is there a difference between the two?>>
Dear Student,A modal verb is a type of auxiliary verb but an auxiliary verb is not necessarily a modal verb.
The term "auxiliary verb" is a larger umbrella term and "modal verb" is under the umbrella.
Examples of English modals: can, could, may, might, must, shall, should, will, would
Examples of ASL Modals: CAN WILL MUST-[should]
Modality: The degree to which something is possible or necessary. [Example: CAN is a modal verb when it is used to indicate possibility. MUST is a modal verb that is used to indicate necessity. The sign WILL can be used at the end of a sentence to indicate that an action is extremely likely or a near certainty.
Also see: Auxiliary Verbs in ASL