Answer :
Large is a noun. Fish is noun. Swim is a verb, it can also be a noun. Swiftly is an adjective, it qualifies a noun. "In" is an irregular verb. "The" is a preposition. Sea is a noun.
Large is an adjective.
Fish is a noun.
swim is a verb.
swiftly is an adverb because it answers the question How
in the sea would be a prepositional phrase. In being the preposition, the being an article, and sea being the object of the preposition.
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