* Nouns as Subjects: Nouns are the actors or subjects of a sentence. They perform the action described by the verb.
* Example: The dog barked. ("Dog" is the noun, "barked" is the verb)
* Pronouns as Replacements: Pronouns can replace nouns to avoid repetition.
* Example: He barked. ("He" replaces "The dog")
So, to answer your question directly:
* Nouns cannot "perform the action of a sentence" They are the *subjects* of the action. Verbs are the words that express the action.
* Nouns can be replaced by pronouns, but the pronoun must agree with the noun in person, number, and gender.
Let me know if you have any other grammar questions!