In the imperative mood the speaker urges the person addressed to fulfill an action. This may be expressed in the form of a command, a request, a warning, etc. [1; 2; 5].
The imperative mood has only one simple form for the second person singular and plural, and is the plain present tense stem of the verb [1; 2; 3; 5; 9]:
E.g. "Just relax, breathe as deeply as you can, everything will be all right.” /Dean Koontz Hideaway/
E.g. “Turn your television set to BBC1, Bridget.” /Helen Fielding Bridget Jones’s Diary/
In the 1st and 3d person the combination let + infinitive, an equivalent of the imperative, is used [1; 2; 3; 5; 9]:
E.g. “Let me make amends,” I begged. /James Herbert Others/
E.g. Their voices come to me on the cold wind, saying, “Stop. Let us help you.” /Chuck Palahniuk Fight Club/
E.g. “Let's face it, Brighton has more than it’s fare share of fortune tellers, not to mention <…> alternative medicine practitioners.” /James Herbert Others/
The subject of the imperative mood is seldom expressed unless it is emphatic. In Modern English it is placed before the verb in the usual place of the subject [1; 2; 3]:
E.g. “You watch it,” he said, “or we’ll call a psychiatric consult.” /Michael Crichton A Case of Need/
E.g. “Don’t you lie to me, angels aren’t allowed to lie.” /Dean Koontz Hideaway/
The negative imperative is formed by means of the auxiliary verb to do even if we have the verb to be, which in the indicative mood does not require that auxiliary [1; 2; 3]:
E.g. “Ugh! God! Don’t drink it. It’s bound to be off.” /Joanne Harris Blackberry Wine/
E.g. "Don't worry, we’ll get Skeet down,” Dusty assured him. /Dean Koontz False Memory/
The emphatic imperative is formed with the help of the auxiliary verb to do, followed by the infinitive:
E.g. "Do sit down." /John Galsworthy/ [1; 2; 3]
Very often the imperative is followed by “Will you?”. In such sentences the order becomes modified by the addition of “will you?” in a kind of request [1; 2; 3]:
E.g. "Give me my box and money, will you?" I cried bursting into tears. /Charles Dickens/ "Heigh! Heigh! Keep that dog back, will you?" he shouted. /George Eliot/
