Question: what are copula and auxiliary verbs?
Answer: Copula verbs are usually called linking verbs, which LINK the (simple) subject to a noun or an adjective in the predicate. EXAMPLES OF EACH: The boy is a student. ... Forms of BE, or "to be" verbs, can also be used as auxiliary verbs: She IS sleeping. The main verb is SLEEPING; the word IS is an auxiliary verb.