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.


 

Exercise

Section: 

Comments

hello
To is infinitive verb marker.. but in this "You can keep it" KEEP is not finite by subject YOU.
but i never heard that anyone says "you can to keep it". could you explain sir what happens in that sentences.

Hello Tharanga pud,

Infinitives are sometimes used with 'to' and sometimes without 'to'; when they are used without 'to' (such as in 'You can keep it'), they are often referred to as a 'bare infinitive' or 'base form'. Verbs that come after modal verbs like 'can' are used in the base form. This is why 'You can keep' is correct and 'You can to keep' is not.

All the best,
Kirk
The LearnEnglish Team

thank you!

Hello.would you tell me when we use simple form after "help"?and when we use to+infinitive?
with best wishes.

Hello rastak keen,

Both forms are fine and mean the same thing; they are alternatives.

I helped him to get into the car.

I helped him get into the car.

 

Best wishes,

Peter

The LearnEnglish Team

hello, is the following sentence correct?
" Did they always use those motor-bikes ? - No, they were used to deliver the mail during the rush-hours"
I woluld have written".....No, they used to deliver the mail during rush-hours"

Hello manuel24,

I would say the most likely form is:

Did they always use those motor-bikes?

No, they used them to deliver the mail during the rush-hour.

You could say 'rush hours' if, for example, you are thinking of several rush hours during the day (one at 09.00, one at 17.00 etc).

 

Best wishes,

Peter

The LearnEnglish Team

Hello ,"I loved my holiday in England, but I didn't like the driving. I did over one thousand kilometres!"
could be used to+infinite instead of "the driving"?

hello, if the rule says " Remember/forget + to + infinitive means that you remember something you have to do – a duty or a chore" so i don't understand this sentence:
Oh dear! I forgot my homework! The teacher will be angry..please help me

Hello manuel24,

The sentence you provide is not an example of this rule as there is a direct object after 'forget' and not an infinitive. Compare:

I forgot my homework. (I didn't bring it with me)

I forgot to do my homework. (I didn't remember to do it)

Best wishes,

 

Peter

The LearnEnglish Team

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