We use the to-infinitive:

• to express purpose (to answer "Why...?"):

He bought some flowers to give to his wife.
He locked the door to keep everyone out.

We sometimes say in order to or in order not to:

We set off early in order to avoid the traffic.
They spoke quietly in order not to wake the children

… or we can say so as to or so as not to:

We set off early so as to avoid the traffic.
They spoke quietly so as not to wake the children.

• after certain verbs (see verbs followed by infinitive), particularly verbs of thinking and feeling:

choose, decide, expect, forget, hate, hope, intend, learn, like,
love, mean, plan, prefer, remember, want, would like, would love

… and verbs of saying:

agree, promise, refuse

They decided to start a business together.
Remember to turn the lights out.

Some verbs are followed by a direct object and the infinitive(see verbs followed by infinitive):

advise, ask, encourage, invite, order, persuade, remind, tell, warn,
expect, intend, would prefer, want, would like

She reminded me to turn the lights out.
He encouraged his friends to vote for him.

• after certain adjectives.

Sometimes the to-infinitive gives a reason for the adjective:

  • disappointed
  • glad
  • sad
  • happy
  • anxious
  • pleased
  • surprised
  • proud
  • unhappy

We were happy to come to the end of our journey
= We were happy because we had come to the end of our journey
John was surprised to see me
= He was surprised because he saw me

Other adjectives with the to-infinitive are:

  • able
  • unable
  • due
  • eager
  • keen
  • likely
  • unlikely
  • ready
  • prepared
  • unwilling
  • willing

Unfortunately I was unable to work for over a week.
I am really tired. I’m ready to go to bed.

We often use the to-infinitive with these adjectives after it to give opinions:

  • difficult
  • easy
  • possible
  • impossible
  • hard
  • right
  • wrong
  • kind
  • nice
  • clever
  • silly
  • foolish

It’s easy to play the piano, but it’s very difficult to play well.
He spoke so quickly it was impossible to understand him.

We use the preposition for to show who these adjectives refer to:

  • difficult
  • easy
  • possible
  • impossible
  • hard

It was difficult for us to hear what she was saying.
It is easy for you to criticise other people.

We use the preposition of with other adjectives:

It’s kind of you to help.
It would be silly of him to spend all his money.

• As a postmodifier (see noun phrases) after abstract nouns like:

  • ability
  • desire
  • need
  • wish
  • attempt
  • failure
  • opportunity
  • chance
  • intention

I have no desire to be rich.
They gave him an opportunity to escape.
She was annoyed by her failure to answer the question correctly.

• We often use a to-infinitive as a postmodifier after an indefinite pronoun (See indefinite pronouns):

When I am travelling I always take something to read.
I was all alone. I had no one to talk to.
There is hardly anything to do in most of these small towns.






It is said that we have such a rule: If an infinitive(intransitive) comes after a noun and that noun is logical object of the infinitive, a prepostion is required:

1. The children need a garden to play in. (followed the rule)
2. There is not enough snow to ski on. (followed the rule)

3. It is difficult to find a place to park. (why not "park in" here? )

Hello sword_yao,

Neither Peter nor I are familiar with this rule. It seems to work in many cases, but not with all. You've already found one counter-example ('place') and the word 'time' (e.g. 'There isn't enough time to go skiing') is another.

All the best,
The LearnEnglish Team

thanks a lot. I do need to realize existence of exceptions.

Thank you very much!!


I would like to ask about a structure of "would prefer".

When referring to the present, it is ok to use it with full infinitive, both when the subject is the same and when there is a change of subject.
I would prefer to stay here.
I would prefer you to stay here.

How about using a similar structure when referring to the past in both cases?
I would have preferred to have stayed here.
I would have preferred you to have stayed here.

Thank you very much!!

Hello kelly,

When referring to the present, the full infinitive is correct in the first sentence but a little unusual in the second. There a past simple form is typically used, and I'd say 'would rather' is more commonly used than 'would prefer' (e.g. 'I'd rather you stayed here').

In the second set of sentences, the first is correct and but the second sounds strange to me. I'd recommend something like 'I´d have preferred that you stayed' (or even 'had stayed').

All the best,
The LearnEnglish Team

What is the difference between the base form and the infinitive of the verb? I know that the base form is the most simple form of a verb, e.g. "go" whereas the infinitive is "to go". With modals verbs, should one say, e.g. "can + base form" or "can + infinitive without to"?

Hello amirfd,

'base form' and 'bare infinitive' and 'infinitive without 'to'' all refer to the same form. It would certainly be easier if thre were just one term, but I'm afraid that's just not the case!

All the best,
The LearnEnglish Team

Infinitive: "to + base form of a verb" or "base form of a verb"?
Different references have different definitions.