The infinitive of purpose – TO

The infinitive of purpose – TO

We use  to + infinitive to say why we do something.  It shows the reason.

Watch out!

We can only use the infinitive of purpose if:

  •  the subject of the main verb and the infinitive of purpose are the same.

I am calling you to ask for your help. (I’m calling you because I want to ask for your help. It’s about me.)


Common (in any tense):

I’m calling you to ask for your help.

I exercise every day to stay healthy.

I was walking to the shops to buy chocolate when I saw him.

He’s gone to the shops to buy me chocolate.

To pass this test, you need to achieve a score of 75% or more.


We use to + infinitive to say why we do something.


More formal:

in order to + infinitive             I’m calling  in order to arrange a meeting.

so as to + infinitive (less frequent)        I’m calling  so as to arrange a meeting.


Summary:

We went on holiday to relax.

We went on holiday in order to relax.

We went on holiday so as to relax.


Watch out!

Do not use for + infinitive.
We went on holiday for relax.


Negative purpose  (more formal):

  • with in order not to / so as not to

I got up quietly in order not to wake the baby.

He closed his bag so as not to lose the money.


SO THAT

  • for negative purpose (even though the subjects are the same, we avoid using in order not to)

I checked the time so that I wouldn’t miss the train.

She usually writes up a shopping list so that she doesn’t forget anything.


  • with CAN, COULD (to avoid using in order to be able to)

I turned on the radio so that I could hear the news.


  • different subjects

I’ll leave the door open so that you can come in.

I went out so that they could prepare the party.


Final trick (to avoid SO THAT)

I left the window open so that the cat could get in

= I left the window open for the cat to get in.

She writes books so that her kids can read something nice.

= She writes books for her kids to read something nice

He worked hard so that his family could have enough money. 

= He worked hard to earn enough money for his family.

  • Czech ABY (Chci abys TY uvařil. Potřebuju aby ONA zůstala doma…)

I need you to help me.         I need that you help me.

I want you to stay here.         I want to that you help me.