1. Form |
The infinitive is the base form of a verb. It may be preceded by 'to' (the to-infinitive) or stand alone (the base or zero infinitive).
2. Infinitive with or without 'to'
The to-infinitive is used:
a. after certain verbs. e.g. want, wish, agree, fail, mean, decide, learn
b. after the auxiliaries to be to, to have to, and ought to
c. in the pattern 'it is + adjective + to-infinitive'
The elephant decided to marry the mouse
The mouse agreed to marry the elephant
You will have to ask her
You are to leave immediately
He ought to relax
She has to go to Berlin next week
It's easy to speak English
It is hard to change jobs after twenty years
It's stupid to believe everything you hear
I would rather visit Rome.
She would rather live in Italy.
Would you rather eat steak or fish?
He would rather work in a bank.
I'd rather be a forest than a tree.
The most common uses of the infinitive are:
To indicate the purpose or intention of an action (where the 'to' has the same meaning as 'in order to' or 'so as to'):
She's gone to collect her pay cheque.
The three bears went into the forest to find firewood.
As the subject of the sentence:
To be or not to be, that is the question.
To know her is to love her.
(Note: this is more common in written English than spoken)
With nouns or pronouns, to indicate what something can be used for, or what is to be done with it:
Would you like something to drink?
I haven't anything to wear.
The children need a garden to play in.
After adjectives in these patterns:
It is + adjective +to-infinitive
It is good to talk
It is + adjective + infinitive + for someone + to-infinitive.
It is hard for elephants to see mice
It is + adjective + infintive + of someone + to-infinitive.
It is unkind of her to say that.
After an adjective + noun when a comment or judgement is being made:
It was a stupid place to park the car.
This is the right thing to do.
It was an astonishing way to behave.
With too and enough in these patterns:
too much/many (+ noun) + to-infinitive
There's too much sugar to put in this bowl.
I had too many books to carry.
too + adjective + to-infinitive
This soup is too hot to eat.
She was too tired to work.
too + adverb + to-infinitive
He arrived too late to see the actors.
enough (+ noun) + to-infinitive
I've had enough (food) to eat.
adjective + enough + to-infinitive
She's old enough to make up her own mind.
not enough (+noun) + to-infinitive
There isn't enough snow to ski on.
You're not old enough to have grand-children!
4. INFINITIVE AFTER QUESTION WORDS
These verbs: ask, decide, explain, forget, know, show, tell, understand, can be followed by a question word such as where, how, what, who, when or 'whether' + the 'to-infinitive'.
She asked me how to use the washing machine.
Do you understand what to do?
Tell me when to press the button.
I've forgotten where to put this little screw.
I can't decide whether to wear the red dress or the black one.
The question word Why is followed by the zero infinitive in suggestions:
Why wait until tomorrow?
Why not ask him now?
Why walk when we can go in the car?
Why not buy a new bed for your bedroom?
Why leave before the end of the game?
Why not spend a week in Beirut and a week in Baghdad?
5. NEGATIVE INFINITIVE
To form the negative infinitive, place not before the to- or zero infinitive:
e.g. not to worry:
It's hard not to worry about exams.
I decided not to go to London.
He asked me not to be late.
Elephants ought not to marry mice.
You'd better not smile at the crocodile.
I'd rather not eat meat.
6. OTHER FORMS
The infinitive can have the following forms:
to have + past participle, e.g. to have broken, to have seen, to have saved.
This form is most commonly found in Type 3 conditional sentences, using the conditional perfect, e.g. If I had known you were coming I would have baked a cake.
Someone must have broken the window and climbed in.
I would like to have seen the Taj Mahal when I was in India.
He pretended to have seen the film.
If I'd seen the ball I would have caught it.
The continuous infinitive:
to be + present participle, e.g.to be swimming, to be joking, to be waiting
I'd really like to be swimming in a nice cool pool right now.
You must be joking!
I happened to be waiting for the bus when the accident happened.
The perfect continuous infinitive:
to have been + present participle
to have been crying
to have been waiting
to have been painting
The woman seemed to have been crying.
You must have been waiting for hours!
He pretended to have been painting all day.
The passive infinitive:
to be + past participle, e.g. to be given, to be shut, to be opened
I am expecting to be given a pay-rise next month.
These doors should be shut.
This window ought to be opened.