The shortest sentences in the English language are imperative sentences. For instance, Stop. Go. and Help! are all imperative. These sentences express a command or request and let others know, in a clear and concise manner, what you would like them to do. They can be short, as seen in the previous sentence, or they can be long and complex (Please make sure you turn off the air conditioner and lock the door before you leave the house). Though they can sometimes double as either exclamatory or interrogative sentences, imperatives have a set of rules all their own.
One of the most interesting aspects of imperative sentences is the subject. Take a look at a few imperative sentences and try to determine the subject:
Take the dog for a walk. Check the mail. Please put gas in the car. Clean your room. Be quiet.
Did you find it? The subject of an imperative sentence is elusive, but it is always there as an implied you. Place you into any of the sentences above and it will become clear that you are expected to perform any action or embody any state.
You take the dog for a walk. You check the mail. You please put gas in the car. You clean your room. You be quiet.
The verb in an imperative sentence is an imperative verb. What this means is that it is always in its base form, much like the infinitive form.
be Be still. live Live well. find Find yourself. give Give generously. walk Walk softly.
Imperative sentences can be turned from a simple command to a specific type of interrogative sentence known as a "tag question" by adding a comma, followed by an auxiliary verb and the subject you. For instance, the imperative Take out the trash. can be converted to a tag question by adding a comma and will you, and ending the sentence with a question mark--Take out the trash, will you?