Identify the infinitive phrase and the subject of the infinitive in the sentence below.
to do one's best is the ultimate goal.

 The correct answer is : The phrase in the infinitive is: To do one's best

The theme is: The triumph is the final goal but the desired, the goal to achieve is "one's best".

Explanation:   A phrase in the infinitive is one that has one or more verbs in infinitive mode. The infinitive is a non-personal verbal form since the verb has no mode, person, time or number. The infinitive is formed with "to" + basic form of the verb. In the case of the sentence of the question, it would be: To do