Linking Verb vs Action Verb

Action or Linking Verb?
Some verbs can be action or linking depending on how they are used in a sentence.
Examples of these words include taste, smell, appear, look, feel, and sound.

How do you tell the difference? Easy! Replace the word with am, is, are, was, or were.
If the sentence still makes sense, the word is being used as a linking verb.
If the sentence doesn’t make sense, the word is being used as an action verb.

examples:
Sentence: Sam looked tired.
Test: Sam was tired.
Conclusion: This sentence still makes sense. Looked is a linking verb.
Sentence: Sam looks at every book carefully.
Test: Sam is at every book carefully.
Conclusion: This sentence does not make sense. Looks is an action verb.