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 everybody!
My question is about "be sent" here, what is the rule that we use infinitive without to here? "It is essential that these application forms be sent back as early as possible."
could you give any other examples?
Thank you!

Hello Zaftig,

In the sentence you ask about, 'be sent' is a passive form. A phrase like 'it is essential that' is followed by a bare infinitive form (e.g. 'it is essential that you book a room in advance'). In this case, the bare infinitive is 'be', which is part of the verb 'send' in the passive form. Another couple examples: 'Application forms must be sent back as early as possible', 'Application forms can be sent by email'.

Hope this helps!

All the best,
Kirk
The LearnEnglish Team

Hi team.
I'm confused how to use to-infinitives as an object (a noun) or an adverb. Ex: I like to travel aboard and I work to make money.
Could you help me distinguishing them.
Thanks.

Hello MinhVu1412,

In your first example, the to + infinitive is the object of the verb 'like', whereas in your second example, the to + infinitive used as an infinitive of purpose. It expresses the purpose of working or the reason 'I' work. 'like' is different. Liking doesn't have a purpose. In other words, we just like things, and some of the things we like are actions (e.g. 'traveling abroad').

Does that help?

All the best,
Kirk
The LearnEnglish Team

I

Thank for replying.
So we must understand what mean the main verb is to decide the to-infinitive that follows is noun or adverb, right?

Hello MinhVu1412,

I suppose you could look at it that way, though with structures like these, I think the best way to learn them is to think of them as patterns. Different words tend to be used with other words and it's useful to know this. Here, for example, it's useful to know that you can use 'like' with a to + infinitive to talk about actions or activities you like. That is how the page above is organised.

Best wishes,
Kirk
The LearnEnglish Team

"what are you doing?" this is present continuous but I've often heard in English films "What do you doing?" Is that my hearing problem? could you explain sir?

Hello raj jk,

I of course can't say what you've heard in films, but I really doubt that what you heard was 'what do you doing', as it really just doesn't work in English. There are plenty of non-standard forms that people use in speaking (e.g. 'Whatcha doing?'), but 'what do you doing' is not one of them, at least that I've ever heard.

All the best,
Kirk
The LearnEnglish Team

hello!
"Nouns are the most common type of word, followed by verbs. " in this sentence What does 'followed by' mean? I am not able to understand it correctly

Hello raj jk,

Here it means 'after', i.e. nouns are the most common type of word and verbs are the second most common. By the way, although you have to look a bit for it, this is explained in the Cambridge Dictionary definition for 'follow' – see the entry for follow (HAPPEN).

All the best,
Kirk
The LearnEnglish Team

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