A noun (Latin nomen, "name") is a word that is used to identify anything that can be named or tells you what is being talked about.
These are identifying words used instead of a noun, i.e. substitutes for nouns.
verb connotes an action, state, or occurrence; forms the main part of the predicate of a sentence
subject refers to a person, place, idea, or thing described, discussed, or otherwise dealt with in a sentence; can be a noun or pronoun together with all of the modifiers that tag along with it; can be found at the beginning, middle, or end of a sentence
To complete a sentence, every verb must have a subject. A verb that expresses an action has a who or what subject. Not all verbs are action verbs because they can be linking or helping verbs which connect the subject to something that refers to the subject.
This refers to the matching in number of the subject and the verb. In other words, they have to agree whether they have to be in plural or singular form.
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