A subject complement is a word or group of words that follows a linking verb and provides additional information about the subject of the sentence. This has an adjective ('happy') that describes or qualifies the subject ('She') = Subject + Linking Verb + Predicate Adjective.

An object complement is a word or group of words that provides more information about the direct object in a sentence, in this case the direct object being 'him' and the information being 'genius' = Subject + Action Verb + Direct Object + Object Complement.

This has an adjective ('delicious') that describes or qualifies the subject ('the meal') = Subject + Linking Verb + Predicate Adjective.

This has a noun ('musician') that renames or identifies the subject = Subject + Linking Verb + Predicate Nominative.

'Interesting' describes the direct object 'book' = Subject + Action Verb + Direct Object + Object Complement.

The direct object is 'John' and 'class president' is the further information about him = Subject + Action Verb + Direct Object + Object Complement.

This has a noun ('lecturer') that renames or identifies the subject = Subject + Linking Verb + Predicate Nominative.

'Max' describes the direct object 'dog' = Subject + Action Verb + Direct Object + Object Complement.

'Confused' describes the direct object 'her' = Subject + Action Verb + Direct Object + Object Complement.

This has an adjective ('beautiful') that describes or qualifies the subject = Subject + Linking Verb + Predicate Adjective.