Locate the complete infinitive phrase and identify its use. David is going to see her again.

Infinitive Phrase: To see her again

Use: Adverb

In the sentence "David is going to see her again", the complete infinitive phrase is "to see her again" and it functions as the object.

An infinitive phrase is composed of a group of words that uses an infinitive: "to" + verb. It has the role of expressing an action in a sentence. Moreover, an infinitive phrase is part of a sentence, so it usually functions as a noun, adjective or adverb.

In the case of the sentence, as the infinitive phrase answers to the question "What is he going to do?", the infinitive phrase functions as the object.