1) WHAT THE THING IS USED FOR
FOR + -ing
TO infinitive
Scissors are for cutting.
It’s good for nothing.
A lawn mower is for cutting grass.
A pen is for writing.
We use this to dry our hair.
2) FOR WHAT PURPOSE THE ACTIVITY TAKES PLACE (THE SAME SUBJECT)
IN ORDER TO + infinitive (used more often)
SO AS TO + infinitive (less common)
!!! Both activities need to have the same SUBJECT!!!
I went to my grandparents in order to help them.
She bought a new car in order to visit her boyfriend in Germany.
We thanked her repeatedly so as to express our gratitude.
NEGATIVE:
IN ORDER NOT TO
SO AS NOT TO
We were whispering in order not to wake our children up.
I will call him immediately so as not to forget it.
!!! Normally, *IN ORDER and *SO AS are omitted and ‘the infinitive of purpose’ is used!!!
I went to my grandparents in order to help them. >> I went to my grandparents to help them.
She bought a new car in order to visit her boyfriend in Germany. She bought a new car to visit her boyfriend in Germany.
I work hard in order to have enough money. >> I work hard to have enough money.
We go on holiday in order to recharge our batteries. >> We go on holiday to recharge our batteries
!!! Negative purposes: *These cannot be omitted. >>> We were whispering in order not to wake our children up. >>> We were whispering not to wake our children up.
!!! If you have a sentence with DIFFERENT SUBJECTS, the above expressions CANNOT be used!!!
3) FOR WHAT PURPOSE THE ACTIVITY TAKES PLACE (DIFFERENT SUBJECTS)
If the purpose has a different subject from the activity, a subordinate purpose clause has to be used.
IN ORDER THAT (more formal)
SO THAT
I come home early so that my daughter can use a car.
We did not come to terms with their conditions in order that they would propose the better ones.
Modal verbs can be used in these sentences too. The tense used in the main and subordinate clause should be the same.
Past tense – past tense (past modal verb)
Present tense/future – present tense (present modal verb)
I often wake up early so that I can exercise before going to work.
I woke up early so that I could exercise before going to work.
SO THAT clauses are usually used:
1) actions having different subject
I whispered so that she couldn’t hear me.
I called him again so that he didn’t have to call me back.
2) Present tenses for future
- we can use present and future
John is going to work early so that he avoids/will avoid the traffic.
I leave my house through the back door so that I don’t meet / won’t meet our
neighbour.
- we sometimes use present tenses for the future:
I’ll go to the shop now so that Marek doesn’t / won’t have to go there after he gets back
from work.
3) Negative purposes
So that … won’t / wouldn’t / don’t / didn’t / mightn’t / shouldn’t
I called him so that he wouldn’t have to call me.
4) Sentences about the past
We use would/could/should/might
- Could/can: We can avoid >> ‘in order to be able to’
Examples: I switched on the radio so that I could listen to the news.
I will go to England so that I can improve my English.
Our team met on Friday evening so that the problem would be solved as
fast as possible.
There is a tendency to use the purpose infinitive, which is used in clauses which have the same subject. If the subject is different, it is necessary to use subordinate clause introduced by so that.
Practise here:
PS: Contact me if you want a Czech version (with examples explained/translated in Czech)