Expressing purpose
When we want to express the purpose of an action (why somebody does something), we
can use the following words and phrases:
to
in order to
so as to
so that
in order that
1. to, in order to and so as to are followed by the infinitive
I had a party to celebrate my 18th birthday.
Security cameras are used in order to catch thieves.
She used an alarm clock so as to wake up early.
2. so that and in order that are followed by a clause (subject + verb)
I wrote a list so that I wouldn't forget anything.
He used sun cream in order that he didn't get sunburnt.
3. All the phrases can be used in the negative form, except to
I always drive carefully in order not to have an accident.
I always eat vegetables and fruit so as not to catch a cold.
I always learn my lessons so that I don't get bad marks.
I always listen to my parents in order that they don't get upset with me.