Guide to English grammar

It hurts just here. This has happened before.

Question wh: Where does it hurt? yes/no: Has this happened before?

19 The imperative

1 Form
The imperative form is the base form of the verb. It is a second-person form. When I say “Come in”, I mean that you should come in. The negative is “do not/don't + base form”, and for emphasis we use “do + base form.

Positive Negative Emphatic

Read the instructions carefully. Come in. Do not remove this book from the library. Don't make so much fuss. Do be careful.

NOTE
We can use other negative words with the imperative.

Never touch electrical equipment with wet hands.
Leave no litter.

2 Use
1 The basic use of the imperative is to give orders, to get someone to do something. The speaker expects that the hearer will obey.

Teacher (to pupils): Get out your books, please.
Doctor (to patient): Just keep still a moment.
Boss (to employee): Don't tell anyone about this.
Traffic sign: Stop.
A practical guide to English grammar 20
2 But an imperative can sound abrupt. There are other ways of expressing orders.
I want you to just keep still a moment.
You must hand the work in by the weekend.
You mustn't tell anyone about this.
We often make an order less abrupt by expressing it as a request in question form.
Can you get out your books, please?
Could you just keep still a moment?
It is generally safer to use a request form, but the imperative can be used informally between equals.