Many of us learned in school that adjectives modify nouns and that adverbs modify verbs. But as we’ve seen, adjectives can also act as complements for linking verbs. This leads to a common type of error: incorrectly substituting an adverb in place of a predicate adjective. An example you’ve probably heard before is:
Because “feel” is a verb, it seems to call for an adverb rather than an adjective.