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is a word that names a person, place, thing, or idea.

Noun

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expresses an action or a state of being. Every sentence must have at least one.

Verb

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describes or modifies a noun or pronoun. It tells you "which one," "what kind," or "how many.

Adjective

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modifies a verb, an adjective, or another adverb. They often end in -ly and answer "how," "when," "where," or "to what extent.

Adverb

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is a word used in place of a noun to avoid repetition.

Pronoun 

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shows the relationship (usually in time or space) between a noun/pronoun and another part of the sentence.

Preposition