English Grammar for the Utterly Confused - Laurie Rozakis 2003

Using Predicate Adjectives after Linking Verbs
Chapter 4. Using Adjectives and Adverbs Correctly
Part 2 Usage and Abusage

A predicate adjective is an adjective that follows a linking verb and describes the subject of a sentence. Remember that linking verbs describe a state of being or a condition. They include all forms of to be (such as am, is, are, were, was) and verbs related to the senses (look, smell, sound, feel). Linking verbs connect the subject of a sentence to a word that renames or describes it.

Use an adjective rather than an adverb after a linking verb. Therefore, use delicious rather than deliciously after the linking verb tastes.

Use an adjective rather than an adverb after a linking verb. Therefore, use bad rather than badly after the linking verb felt.

Use an adjective rather than an adverb after a linking verb. Therefore, use awful rather than awfully after the linking verb look.

Since is (a form of to be) is a linking verb, you must use the adjective happy, not the adverb happily.

Quick Tip

Some verbs do double duty: Sometimes they function as linking verbs, but other times they function as action verbs. As linking verbs, these verbs use adjectives as complements. As action verbs, these verbs use adverbs as complements.