Grammar Handbook: Complements

The Center for Writing Studies, The University of Illinois at Urbana-Champaign

A complement is called a complement because it completes the predicate in a sentence. There are two kinds of complements: object complements and subject complements.

:: Object Complements
An object complement follows the direct object and modifies or refers to the direct object. An object complement can be an adjective, a noun, a word, or a group of words which acts as an adjective or noun:

If you elect me president, I'll keep the unions satisfied.
("President" is an object complement referring to the direct object "me." "Satisfied" is an object complement modifying the direct object "unions.")

The students elected Mary president.
("President" is an object complement referring to the direct object "Mary.")

Wool socks will keep your feet very warm.
("Very warm" is an object complement modifying the direct object "your feet.")
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:: Subject Complements
A subject complement follows a linking verb and modifies or refers to the subject. A subject complement can be an adjective, a noun, a pronoun, a word, or a group of words which acts as an adjective or noun:

I am a teacher, but I am not yet experienced.
("Teacher" and "experienced" are both subject complements that
modify the subject "I.")

Subject complements have two subgroups: predicate adjectives and predicate nouns.

: Predicate Adjectives
A predicate adjective is a subject complement that is an adjective (see appositives):

I am not yet experienced.
("Experienced" is a predicate adjective that modifies the subject "I.")

: Predicate Noun
A predicate noun (nominative) is a subject complement that is a noun:

I am a teacher.
("Teacher" is a predicate noun that refers to the subject "I.")
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