1. Be-verbs: These are forms of the verb "to be": *am, is, are, was, were, being, been*.
* They are used to form continuous tenses (e.g., *I am running*, *She was sleeping*) and passive voice (e.g., *The book was written by John*).
2. Have-verbs: These are forms of the verb "to have": *have, has, had, having*.
* They are used to form perfect tenses (e.g., *I have finished*, *He had gone*).
3. Do-verbs: These are forms of the verb "to do": *do, does, did, doing*.
* They are used for emphasis (e.g., *I do like pizza*), in questions (e.g., *Do you understand?*), and in negative sentences (e.g., *I don't want to go*).
It's important to note that these verbs can also act as main verbs in a sentence, but when they do, they are not considered auxiliary verbs.