Unit 60. Infinitive of purpose – “I went out to mail a letter.” So that…

A.
We use the infinitive (to do) to talk about the purpose of doing something (= why someone does something): .

  • I went out to mail a letter. (= because I wanted to mail a letter)

  • She called me to invite me to a party.

  • We shouted to warn everyone of the danger.

    We also use the infinitive to talk about the purpose of something, or why someone has/ wants/needs something:

  • This wall is to keep people out of the garden.

  • The President has two bodyguards to protect him.

  • I need a bottle opener to open this bottle. You can also use in order to (do something):

  • We shouted in order to warn everyone of the danger. Do not use for in these sentences:

  • I’m going to Mexico to learn Spanish, (not for learning / for to learn)

    B.
    We also use the infinitive to say what can be done or must be done with something:

  • It’s usually difficult to find a place to park downtown. (= a place where you can park)

  • Do you have a lot of work to do this evening? (= work that you must do)

  • Would you like something to eat?

  • There were no chairs to sit on, so we all had to sit on the floor.

  • She is lonely. She has nobody to talk to.

    We also say time/opportunity/chance/money/energy to do something:

  • They gave me some money to buy some food, (not for buying)

  • Did you have time to answer all the questions on the exam?

  • These days I don’t get much chance to watch television. I’m too busy.

  • Do you have much opportunity to speak English? (= much chance to speak)

    C.
    Sometimes you have to use so that (not the infinitive) to talk about the purpose of doing something.

    We use so that:

    i) when the purpose is negative (so that… won’t/wouldn’t…):

  • I hurried so that I wouldn’t be late. (= because I didn’t want to be late)

  • Leave early so that you won’t (or don’t) miss the bus.

    ii) with can and could (so that… can/could…):

  • He’s learning English so that he can study in the United States.

  • We moved to London so that we could visit our friends more often.

    iii) when one person does something so that another person does something else:

  • I gave him my address so that he could contact me.

  • He wore glasses and a false beard so that nobody would recognize him.
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