Imperative sentences are used for many reasons:

Reason Example
arrrow to the right to give advice or suggestions Exercise four times a week.
Don’t eat too much chocolate.
arrrow to the right to give directions Turn right at the bank and walk three blocks.
arrrow to the right to give instructions Cut the onions into small pieces and fry in oil.
Save your document and put it in a new folder.
arrrow to the right to give orders or commands (Please) be quiet!
Do your homework.
arrrow to the right to give warnings Watch out!
Don’t drive after drinking.
arrrow to the right to make a polite request Please turn off the light, Mary.
Close the window please, Janice.
arrrow to the right to offer an informal invitation Bring a friend to the party if you like.
Join us for dessert, Cathy!

Notice that the subject of these sentences (you) is not written or spoken. It is the same for singular and plural subjects.

(You) turn left at the corner and drive two kilometers.

Sally and Mark, stand up please.

In order to make the negative form, simply say:

“Do not + simple verb...” or “Don’t + simple verb...”

Do not run across the road, children.

Don’t smoke in the airport please.

Be careful! Do not use the imperative in formal situations with an employer or a teacher. The imperative is too direct.

Come to lunch Mrs. Rivers.  arrrow to the right  Wrong!

Would you like to join us at lunch, Mrs. Rivers?  arrrow to the right  Good!

When you are sure that you understand the lesson, you can continue with the exercises.