Infinitive

by Teng Sam An

An infinitive is a verbal which is formed by "to + verb". Although it looks like a verb, an infinitive functions in a sentence as  a noun, an adjective, or an adverb -- not a verb.

For examples,

• To write an informal letter is quite easy. [noun subject]
• Most students plan to study abroad. [noun object]
• His plan to own a business is delayed due to financial reason. [adjective]
• I am happy to meet you. [adverb]

Functions of infinitives

Again, an infinitive can function as noun, adjective or adverb. 

1. As a Noun

It can be used as subject, subject complement, direct object, and object of preposition.

a. Subject

For examples,

• To read is so important.
• To get a scholarship needs preparations.

b. Subject complement (predicate nominative, standing after verb to be)

For examples, 

• His ambition is to fly. 
• Our priority now is to research the market.

c. Direct object

For examples, 

• She's committed to win. 
• The guy promised to return the money.

The common verbs followed by an Infinitive are: afford, agree, aim, appear, arrange, ask, attempt, be able, beg, begin, can’t bear *, care, claim,  choose, condescend, consent, continue, dare, decide, deserve, demand, detest, dislike, expect, fail, forget *, get, happen, hate *, hesitate, hope, hurry, intend, leap, leave, like *, long, love *, mean, manage, need, neglect, offer, ought, plan, prefer*, prepare, pretend, proceed, promise, propose, refuse, regret *, remember, seem, shoot, start *, stop, strive, swear, threaten, try *, use, volunteer, wait, want, wish,... 
 
Note: Those are marked with asterisk ( * ) can also be followed by gerund

d. Object of preposition (prepositions: except and but )

For examples, 

• We have no choice except to accept their conditions.
• Nothing is left for us but to pack up our belongings and leave.

e. in Infinitive clauses
 
For examples, 

• They asked me to bring some food. [ "me" is an actor ]
• Everyone wanted Rita to be the team leader. [ "Rita" is an actor ]
• Everyone expected her to win.  [ "her" is an actor ]

The common verbs followed by an object and an Infinitive are: advise, allow, ask, beg, bring, build, buy, cause, challenge, choose, command, convince, dare, direct, encourage, expect, forbid, force, have, hire, instruct, invite, lead, leave, let, like, love, motivate, need, order, pay, permit, persuade, prepare, promise, remind, require, send, teach, tell, urge, want, warn,... 

Note: However, there are some Verbs that take infinitive objects without actors, but express slightly different meaning :
 
For examples, 

• I asked him to write a letter. [ I told someone to write the letter. ]
• I asked to write a letter. [ I asked for permission to write the letter. ]

2. As an Adjective 
 
The infinitive is often an adjective used to help define an abstract noun (see the list below).

For examples, 

• It was a good idea to change the key words. 
• The possibility to attract new customers is obvious now.
• The company has no strength to resist the price competition.

Here are some common abstract nouns used with infinitive: advice, appeal, command, decision, desire, fact, instruction, motivation, opportunity, order, permission, plan, possibility, preparation, proposal, recommendation, refusal, reminder, request, requirement, suggestion, tendency, wish, ... 


3. As an Adverb

a. Modifying a verb

For examples, 

• He rushed to finish the sales report. [ Adv: reason modifies verb "rushed" ]
• We must research to find out the trend. [Adv: reason modifies verb "research" ]

b. Modifying an adjective

For examples, 

• They were anxious to begin the adventure.
• She was delighted to receive such good feedback.
• I am lucky to have such good friends like you.

Here are some adjectives normally found in this constructions: ahead, amazed, anxious, apt, ashamed, bound, careful, certain, content, delighted, determined, disappointed, eager, eligible, fortunate, glad, happy, hesitant, liable, likely, lucky, pleased, proud, ready, reluctant, sad, shocked, sorry, surprised, upset,...

c. Expressing the idea of "in order to do something"

For examples, 

• She resigned to run her own business. [ in order to run ] 
• He bought a new Iphone to prove he is stylish. [ in order to prove ]

d. too + adjective / adverb + to infinitive

For examples, 

• The box is too heavy to carry.
• The television is too expensive to buy.
• We arrived too late to see the beginning of the movie.

e. adjective/adverb + enough + to infinitive

For examples, 

• He is old enough to know what is right and wrong.
• They didn't do hard enough to achieve the sales target.

f. enough + noun(s) + to infinitive

For examples, 

• He has enough money to buy his own car.
• We need enough people to start new project. 

INFINITIVE WITHOUT "TO"

We use the infinitive without to in the following cases.

a. after auxiliaries/modals: can, could, may, might, must, shall, should, will, would…

For examples, 

• He can run very fast.
• It may rain this afternoon.

b. after ‘to do’

For examples, 

• I don't know.
• I do like the performance.

c. after the following expressions

• had better       ==> You had better clean your room.
• would rather   ==> Rita would rather study for her exam tomorrow.
• would sooner ==> I would sooner read a book than watch this film.
• why not           ==> Why not ask your neighbors for help?   
• why should we      ==> Why should we go by car?
• why should we not ==> Why should we not go by car?

d. after verbs of perception + object (action has finished)

For examples, 

• She feels the rain fall on her face. 
• I heard the boy shout.
• He watched the thieves steal a car.

e. after let + object

For examples, 

• Maria let her daughter decide on her own.
• Let's go for a walk through the park.

f. after make + object
 
For examples, 

• His father made him do the homework.
• He makes his secretary prepare the reports.