Final answer:
In the given sentence, 'every day' is an adverb describing the frequency of the action, not an adjective, noun, or auxiliary. It is part of a sentence where 'to listen' is the main verb and does not fall under the 'be' verb pattern.
Step-by-step explanation:
In the sentence 'They listen to music every day,' the phrase 'every day' functions as an adverb describing the frequency with which the action of listening to music occurs. It is not an adjective because it does not modify a noun; it's not a noun itself as it does not refer to a person, place, thing, or idea; and it is certainly not an auxiliary since it doesn't help to form different tenses, moods, or voices of other verbs.
In the context of Sentence Patterns with the verb 'to be', when a form of 'be' (am, is, are, was, were) serves as the main verb of a sentence, it is typically followed by an adverbial of time or place, an adjectival, or a noun phrase. However, the verb 'to listen' in the sentence provided does not fall under the 'be' verb category, and thus, 'every day' is not following a 'be' verb but rather gives additional information about the verb 'to listen'.
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