Here's why:
* Linking verbs connect the subject of a sentence to a noun, pronoun, or adjective that describes or renames the subject. They don't show an action.
Example:
* "The sky is blue." (The linking verb "is" connects the subject "sky" to the adjective "blue" which describes the sky.)
* "She is a doctor." (The linking verb "is" connects the subject "she" to the noun "doctor" which renames her.)
Action verbs, on the other hand, describe an action being performed.
Example:
* "He runs quickly." ("Runs" is the action verb describing what he is doing.)
Let me know if you have any other grammar questions!