Predicates in English grammar are words or phrases that express the action performed by the grammatical subject or the state of the grammatical subject.
Predicate is a grammatical function.
The grammatical form that can function as the predicate in English grammar is the verb phrase.
The predicate is the head of the main clause.
Other grammatical functions that appear in the verb phrase of the predicate include progressives, perfects, passives, modals, and operators. Other constituents of the predicate include subject complements, direct object, object complements, indirect objects, and verb phrase complements.
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Hopper, Paul J. 1999. A short course in grammar. New York: W. W. Norton & Company.
Huddleston, Rodney. 1984. Introduction to the grammar of English. Cambridge: Cambridge University Press.