An infinitive phrase is a group of words consisting of an infinitive, modifier and complement.  Infinitive phrases can act nouns, adjectives, or adverbs. The infinitive phrase can be a subject, an adjective, an adverb, a direct object, or a predicate nominative in a sentence.

 

Examples:

(1) As a subject

  • To jog in the park is what I look forward to at most weekends.
    (To jog is an infinitive, and to jog in the park is an infinitive phrase. The infinitive phrase functions as a noun phrase which takes the role of a suject in a sentence.)

(2) As an adjective

  • I have my car to wash before dinner.
    (To wash is an infinitive, and to wash before dinner is an infinitive phrase. The infinitive phrase functions as an adjective phrase modifying the noun car in the sentence.)

(3) As an adverb

  • We have decided to eat out tonight. 
    (To eat is an infinitive, and to eat out tonight is an infinitive phrase. The infinitive phrase functions as an adverbial phrase modifying the verb phrase have decided in the sentence.)

(4) As a direct object

  • We need to visit the museum. 
    (To visit is an infinitive, and to visit the museum is an infinitive phrase. The infinitive phrase functions as a noun phrase and acts as a direct object in the sentence.)

(5) As a predicate nominative

  • His great ambition was to bring dinosaurs back to life.
    (To bring is an infinitive, and to bring dinosaurs back to life is an infinitive phrase. The infinitive phrase functions as a noun phrase and acts as a predicate nominative that identifies ambition in the sentence.)

 

Infinitive phrase includes direct and indirect objects

Examples:

  • Nick agreed to lend me some money.
    (Infinitive phrase = infinitive + indirect object + direct object: The infinitive phrase to lend me some money acts as the direct object of the verb agreed. Me is the indirect object of the infinitive to lend, while some money is the direct object of the same infinitive.) 

 

‘Subject’ of infinitive phrase

Examples:

  • He ordered them to clear the path.
    (Infinitive phrase = 'subject' of infinitive phrase + infinitive + direct object of infinitive: The infinitive phrase them to clear the path acts as the direct object of the verb ordered. Them is the 'subject' of the infinitive phrase. The path is the direct object of the infinitive to clear.)

  • They chose Tom to be the leader of the group.  
    (Infinitive phrase = 'subject' of infinitive phrase + infinitive + subject complement + prepositional phrase: The infinitive phrase Tom to be the leader of the group acts as the direct object of the verb chose. Tom is the subject of the infinitive phrase. To be is the infinitive, the leader is the 'subject' complement for Tom, and of the group is the prepositional phrase which functions as an adjective modifying the noun leader.)

 

In the last two examples, the word subject is in inverted commas because it is not really a subject. An infinitive phrase is not a complete clause with a subject and a verb; it therefore cannot have a subject. Another reason is them in the first example is in the objective case, when a subject should be in the subjective case.