An infinitive is a verb form that is typically preceded by the word “to” and functions as a noun, adjective, or adverb in a sentence. An infinitive phrase is a group of words that begins with an infinitive and includes any objects or modifiers associated with the infinitive.

Here are some examples of infinitive phrases:

• To learn a new language (infinitive: “to learn”; object: “a new language”)
• To cook dinner for my family (infinitive: “to cook”; object: “dinner”; modifier: “for my family”)
• To run a marathon (infinitive: “to run”; object: “a marathon”)
• To read in the library (infinitive: “to read”; modifier: “in the library”)

In each of these examples, the infinitive phrase is functioning as a noun, adjective, or adverb in the sentence. It can be the subject of the sentence, the object of a verb, or the object of a preposition. The infinitive in the phrase is the main focus of the phrase, and the objects or modifiers provide additional information about the infinitive.