Infinitive is a verbal made up of the word "to" plus a verb, still with a prepositional phrase starting with the word "to" which make up a "to" plus a noun or pronoun and any modifier. Some examples of infinitives are to eat, to climb, to dance, to wash and a lot more. Furthermore, an infinitive phrase is a group of word with and infinitive or infinitives plus a modifier or modifiers, a noun, pronoun, noun phrases that serves as the actors, direct or indirect object or objects. In the sentence above the infinitive phrase is b. to come back soon.
