Identify the adverb in the sentence: "He quickly finished his homework."

In the sentence "He quickly finished his homework," the word "quickly" functions as an adverb because it describes how the action of the verb "finished" was performed. Adverbs modify verbs, adjectives, or other adverbs by providing additional details about the manner, time, frequency, or degree of the action. In this case, "quickly" specifically indicates the speed at which the homework was completed, giving insight into the manner of the action. The other words in the sentence serve different grammatical purposes; for example, "finished" is the verb indicating the action taken, while "his" is a possessive pronoun and "homework" serves as the noun receiving the action. Hence, "quickly" is the correct identification as an adverb.