"to ~, so as to~, lest should"

I work out to lose weight these days.
I study English to improve long time.

I ran fast so as to be on time for the train.
I have a look the baked fish many times so as not to burn.

I went to the travel agency in order to get some information.
I drink a medicine in order to get over cold.

I saved money so that I might buy a present for him.
I turn on the humidifying system so that it might be more humid.

I was waiting there for the purpose of meeting him.
I went to the grocery store for the purpose of buying a bread.

I was careful not to make a mistake.
I washed up my face not to sleep.

I had to hurry so as not to be scolded for being late.
I clean up my room so as not to be dirty.

I kept an eye on him lest he should break his promise with me.
Streaming the music lest my husband should be boring.