The infinitive with to answers the question “Why?”. It gives the purpose of an action, and the subject of both verbs is the same. “In order to” and “so as to” are more formal and are needed for the negative.
Form
| Structure | Example |
|---|---|
| to + base verb | I went to the shop to buy milk. |
| in order to / so as to + base verb | She studied in order to pass. |
| (in order) not to / so as not to | He spoke quietly so as not to wake her. |
When to use it
- Purpose with the same subject: I use my phone to take photos.
- The use of a thing: A key is used to open a door.
- Answering “Why?”: — Why are you here? — To meet a friend.
- Negative purpose: in order not to, so as not to.
Examples
- I went to the shop to buy milk.
- She called to ask about the meeting.
- We use a knife to cut bread.
- I came here in order to learn English.
- He left early so as not to be late.
- Why did you call? — To say thank you.
Common mistakes
- “For” + verb: I went for to buy bread → to buy.
- “For” + -ing is for the general use of a thing: A knife is for cutting (not a person's purpose).
- Negative with “not to” only: I left early not to be late → so as not to be late.