Here's a breakdown of the main auxiliary verbs and why it's tricky to give a definitive list:
Primary Auxiliary Verbs (always auxiliary)
* be (am, is, are, was, were, being, been)
* have (have, has, had, having)
* do (do, does, did, doing)
Modal Auxiliary Verbs
* can, could, may, might, must, shall, should, will, would
Semi-Auxiliary Verbs
* used to, ought to, have to, need to, be going to, be about to, be supposed to, had better
Why the number is unclear:
* Semi-auxiliary verbs: Some grammarians consider these to be combinations of auxiliary and main verbs, not true auxiliary verbs.
* Phrasal verbs: Some verbs can function as auxiliaries in certain contexts, making it difficult to create a complete list. For example, "get to" can be used like an auxiliary in "I get to go to the party."
Important Note: Auxiliary verbs are essential for forming different tenses, moods, and voices in English. They help express concepts like obligation, possibility, permission, and more.