Infinitive of purpose

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 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 tom 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 would'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.