Linking Words of Purpose

The infinitive of purpose

a) To infinitive

We can use the to infinitive to express purpose (why?).

I went to the shop to buy some fruits. (Why? To buy some fruits.)

Peter studies hard to pass his exam.

She switched off the light not to waste electricity.

Note: The subject of the two verbs is the same: I went and I bought.

Note: In the negative, we use not to.

b) In order to and so as to

If we want to express purpose, we can also use in order (not) to and so as (not) to. They are the formal versions of to.

He turned the radio on

in order to

so as to

listen to the news

She closed the window

in order not to

hear the noise.

We wrote down the address

so as not to

forget it.

c) In order that and so that

If the grammatical subjects of the two parts of the sentence are different, we use so, in order that and so that.

I emailed the photos to Jane so that she could look at them.

Frank cleaned the house in order that he could make Jane happy.

We bought the tickets online so we could save money.

Note: We often use could in the second clause of the sentence.

d) For

We use for to describe how something is used. We have to use for+noun or for+gerund.

This switch is for the electricity.

This course is for learning about grammar.

I went to the office for a meeting.

We went out for a meal.