Could you explain what an action or a linking verb is? I know that a verb is what you do, so what are action and linking verbs?

see below

1. grows – action verb
2. looked – action verb
3. is – linking verb
4. are – linking verb
5. appears to be – linking verb

An action verb shows action or tells what the subject does.

A linking verb links or connects the subject to either a predicate noun or a predicate adjective. A linking verb is usually a form of the BE-verb. However, other non-BE- can also be used as linking verb.

To check if a verb is linking, try substituting it with a BE-verb. If the sentence retains its meaning, then that verb is a linking verb.

Try sentence 5 above.

Sheila appears to be in first place in this race. Sheila is in first place in this race.

(Note: The sentence retained its meaning, so the verb is linking.)