What is the function of the complement shown in parentheses in this sentence?- "Steven seems (unconcerned) about his grades"?
The adjective "unconcerned" is functioning as a subject complement.
A subject complement is a noun, a pronoun, or an adjective that follows a linking verb to restate the subject.
A linking verb acts as an equal sign, the subject is or becomes the object.
-- Mary is my sister. (Mary = sister)
-- Mary looks happy. (Mary = happy)
There are two types of subject complement:
-- a predicate nominative is a noun or a pronoun that follows a linking verb;
-- a predicate adjective is an adjective that follows a linking verb.
The adjective "unconcerned" is a predicate adjective:
-- Steven = unconcerned