When teaching the difference between auxiliary verb and linking verb, it can be pointed out that

• A. A linking verb goes with a main verb
• B. An auxiliary verb goes with a main verb
• C. An auxiliary verb can stand alone
• D. Linking verbs replace the main verb

Answer: (B)

Auxiliary verbs accompany a main verb to show tense, aspect, mood, or voice, forming a verb phrase that carries the grammatical sense beyond the main action. For example, in “She has finished her homework,” the auxiliary has with the main verb finished expresses the present perfect. In “She is running,” is helps form the present progressive with running, signaling ongoing action. A linking verb, by contrast, connects the subject to a description or state rather than helping a main action verb express time. In “The soup tastes delicious,” tastes links the subject to the adjective delicious. So the idea that an auxiliary verb goes with a main verb best captures how auxiliaries combine with the main verb to convey time and other nuances, which is different from how linking verbs connect the subject to description.