1.    1.   Mood
v  Mood is a grammatical category used in many languages to indicate something about the relationship of a sentence’s meaning to the fact of the real world (or some imaginary world).
v  A mood that is used primarily in statements (to communicate information about the world) is called INDICATIVE MOOD.
v  A mood that is used primarily in commands (to exert some influence over the world) is called IMPERATIVE MOOD.
v  Other languages don’t make the division so much between the statements and commands, but  have two moods that distinguish between what is real (REALIS MOOD) and what is less than real (IRREALIS MOOD). Depending on the language, IRREALISmay include commands, wishes, hypothetical and/or contrafactual statements, future time (which is not yet real), and statements over which the speaker indicates doubt or uncertainty. that is, if a language has a special irrealis mood, it would typically be used in the translations of some or all of the following clauses:
(1)   Commands
       Go to bed!
       God, please make it rain!
       Live like a king!
(2)  Wish
      May my baby go to bed early!
      (I hope) it rains tomorrow…
      Long live the king!
(3)  Purpose
      (Get dressed) so you can go to bed.
      (The shaman offered a sacrifice) to make it rain.
      (He worked very hard) to become king!
(4)   Hypothetical
      If you go to bed…
      If it rains to morrow…  
      If he becomes the next king…
(5)   Contrafactual
      If you had gone to bed…
      If it had rained yesterday …
      If I was a king …
(6)  Future
      You will go to bed at 8:00.
will rain later this week.
      He will become king on the death of his mother, the current queen.
(7)  Uncertain
      (I think) that he may have gone to bed.
      (It is reported that it rains everyday in June (but I will not vouch for this fact
      His reign will (probably) be long and illustrious.
7.2.   Prototypical semantics of commands
v  There is a surprising similarity in the way languages form commands. this stem from two basic semantic facts about commands:
  • the subject of a command is second person
  • a command refers to future time
v   these can be seen in English not just in the meanings of commands, but also in their grammatical structure. why do we say tat the subject of a command is second person, when the subject is normally omitted? of course, that is the understood meaning of a command. for instance, in the English commands below, the agent who is intended to perform the action is clearly you.
(8)  a. Shut up!
      b. Stop it!
      c. Pleasebrush your teeth – your breath stinks!
But, in addition to these philosophic concerns, there is some linguistic evidence in English that commands are grammatically future. Future time is indicated in English with the auxiliary verb will. It is omitted from an imperative clause, but reappears when a tag is added to a command.
(9)   Come here, will you!
7.3   English Commands
Commands in English differ from statements in three ways, all related fairly directly to the universal factors noted above. The first is syntactic the other two morphological.
a. The subject NP is usually omitted.
b. All overt indication that the subject is second person is removed from the verb.
c. The verb is not marked for tense.
The lack of agreement and tense morphology can be seen most clearly with the copula to be. This verb has more forms than most verbs, it varies depending on tense and the person and number of the subject.
I                                   am
He/she/it                    is
We/you/they              are
i/he/she/it                  was
we/you/they               were
however, in commands we find none of these forms. Instead, we get only the stem form be, sometimes called the INFINITIVE.
(10)   Be quiet!
Whenever this form be
is used, it expresses nothing about person, number, or tense. In other words, imperative verbs use a special morphological form, the infinitive, which does not mark as many grammatical categories as ordinary verb forms.
         In English commands the subject NP (you) is usually omitted.  We need some of stating that it is just in commands that the subject can be omitted. What we need is a transformation, one which deletes the subject you only in commands. That is, we assume that the deep structure of a command always has you as its subject and that the transformation, called IMPERATIVE SUBJECT DELETION, optionally deletes the subject if the verb has been marked [+imperative]
       As an example of how this rule works, consider how we might generate the command ‘Go home!’ Our phrase structure rules and lexicon would produce the following deep structure:


Note that the inflectional features on the verb are the only difference between (11) and the deep structure of the corresponding statement ‘You go home’.
In this tree is allowed to surface without being affected by imperative Subject Deletion, the eventual result is the grammatical command ‘You go home’. More commonly, however, the transformation does not apply and the result is a sentence with the following structure: