An adjective in the predicate belonging to a noun or pronoun in the subject is called a predicate adjective.
A predicate adjective completes the meaning of the predicate verb and is therefore a complement.
Like the predicate nominative, the predicate adjective is common after copulative verbs and after certain transitive verbs in the passive voice.
1. John was angry.
2. My knife is growing dull.
3. The task seemed very easy.
4. The report proved false in every particular.
5. The boat was thought unsafe.
6. The cover was made perfectly tight.
In some of these examples, the predicate adjective has a modifier. In the third, easy is modified by the adverb very. In the fourth, false is modified by the adverbial phrase in every particular. In the last, tight is modified by perfectly.
An adjective phrase may be used as a predicate adjective. Thus…..
1. Richard was out of health. [Compare: Richard was ill.]
2. Rachel seemed in a passion. [Compare: seemed angry.]
3. This act is against my interests. [Compare: is harmful to me.]
The adjective phrase may consist of an infinitive with or without the preposition about.