Question

his idea of a perfect afternoon is to fish. subject predicate nominative adverb

Explanation:

To determine the correct label, we analyze the sentence structure. In the sentence "His idea of a perfect afternoon is to fish", the phrase "to fish" follows the linking verb "is" and renames or describes the subject ("His idea..."). A predicate nominative is a noun or noun phrase that follows a linking verb and identifies or explains the subject. "To fish" (a verbal phrase functioning as a noun here) acts as the predicate nominative. "Subject" would refer to "His idea of a perfect afternoon", and "adverb" is incorrect as "to fish" does not modify a verb, adjective, or other adverb.

Answer:

predicate nominative