Locate the complete infinitive phrase and identify its use. the children were asked to play quietly

to play (functions as a direct object)

Infinitive phrase: to play quietly

Use: direct object

Explanation:

A infinitive phrase consists of a full or bare infinitive verb which is usually followed by a complement and a modifier.

In this case, the infinitive phrase to play is succeeded by the adverb quietly, which functions as a modifier. Besides, infinitive phrases can act as nouns, objects and complements. In the example sentence, the infinitive phrase to play quietly works as the direct object of the passive verb were asked.