Verbs: the Infinitive

Infinitive is the base form of a verb. It has some properties of the verb because it names an action or state but it cannot show person, number, or mood.

Types of Infinitive

Infinitives may be used with the particle ‘to’ in front of it (‘full infinitive’) or without ‘to’ (‘bare infinitive’):

full infinitive	bare infinitive
to be to have to make to sleep to go	be have make sleep go

Infinitives and Prepositional Phrases

Be sure not to confuse an infinitive — a verbal consisting of ‘to’ plus a verb — with a prepositional phrase beginning with ‘to’, which consists of ‘to’ plus a noun or pronoun and any modifiers.

• Infinitives: to fly, to draw, to become, to enter, to stand, to catch, to belong
• Prepositional Phrases: to him, to the committee, to my house, to the mountains, to us, to this address

Full Infinitive

Although infinitive is based on a verb, it may function as a subject, direct object, subject complement, adjective, or adverb in a sentence.

When to use a full infinitive

Full infinitive may be used in a sentence in several ways:

1) as a subject of a sentence

• To err is human, to forgive divine.

2) in a phrase that expresses some purpose or intent

• My plan is to go to the zoo tomorrow.

3) after an indirect object

• My secretary told me to call you back.

4) after certain other verbs, like attempt, choose, decide, hope, manage, plan, promise, refuse, seem, and more:

• She attempted to find a free place in the hall.
• I hope to meet you here next month.
• Mike promised to be more attentive at school.

Learn about the functions of infinitive in a sentence here.

Bare Infinitive

When to use a bare infinitive

Bare infinitives are used:

1) after modal verbs (except for ought to, have to, be to)

• You should wear a warm coat.

2) after will/shall

• I shall call her tomorrow.

3) after verbs of perception

• She heard the door close.

4) after the verbs ‘let’, ‘make’, have’

• Let him behave the way he wants.

5) after the expressions ‘would rather’/had better’

• I would rather go to the cinema.

6) to form imperatives

• Enjoy your stay at our hotel!
• Pass me the salt, please.

Here’s an interesting video about infinitives:

See also:

Uses of Infinitive

Verb Patterns: Verb+Gerund vs Verb+Infinitive