Negative Inverted Construction

Negative inversion, also referred to as declarative negative auxiliary inversion (NAI) in Lisa Green's work, refers to declarative clauses in which a negated auxiliary or modal precedes a quantificational (or indefinite) subject, as exemplified in (1):
(1) a. Can't nobody beat 'em.
     b. Didn't nobody get hurt or nothin'.
     c. Won't anybody hit us.
     d. Cain't all o' ya go at once.

Negative inversion constructions always have a well-formed non-inverted counterpart. Sentences exhibiting negative inversion are given in the (a) examples and their non-inverted counterparts are given in the (b) examples.
(1)  a. Ain't nobody know about no club.
       b. Nobody ain't know about no club.
(2)  a. Didn't everybody go to the party.
       b. Everybody didn't go to the party.


In the southern white speaker varieties, negative inversion constructions are compatible with expletives.
(1)  a. They didn't nobody like him.
       b. They can’t many people say that.
       c. We don't any of us need anything.
       d. There didn't five of em go to sleep, and I thought they was gonna be trouble

Negative inversion constructions are incompatible with expletives in African American English, as in (16).
(1)  a. *There didn't nobody laugh.
       b. *It can't no man round here get enough money to buy they own farm.
       c. *Dey didn't nobody see it.
       d. *It don't nobody be drinking tea.

Negative inversion is often said to co-occur with negative concord in African American English. The co-occurrence typically refers to the availability of subjects headed by no, as in the (a) examples, and the unavailability of subjects headed by NPI any, as in the (b) examples.
(1)  a. Don't nobody break up a fight.
       b. *Don't anybody break up a fight.

Other types of subjects that are not negative are possible, such as subjects headed by a andmany.
(1)  a. Ain't a damn thing changed.
       b. Don't many of them live around here.

In the southern white speech varieties, however, both subjects headed by no and subjects headed by any are possible.
(1)  a. Hain't nobody hardly believed it.
       b. Dudn't anybody seem to understand.
(2)  a. Won't none of the students go to the party.
       b. Didn't any of them answer the question.

In the literature on African American English, negative inversion constructions are distinguished from existential negative inversion in which the auxiliary is the copula be(henceforth existential 'be'). The two constructions look superficially similar, as a negated copula occurs clause-initially and is followed by an indefinite subject. Some examples of existential 'be' constructions are given in (1).
(1)  a. Wasn't nobody home.
       b. Ain't no farmer made money this year.

 It can be difficult to tell the two constructions apart because ain't can have several meanings. It can be the negative copula be+n't, but it can also be the negative perfect auxiliary corresponding to have+n't in Standard English or the negative past tense auxiliary do+n't.

refference
http://microsyntax.sites.yale.edu

Subjunctive

The subjunctive is a special, relatively rare verb form in English.

Structure of the Subjunctive

The structure of the subjunctive is extremely simple. For all verbs except the past tense of be, the subjunctive is the same as the bare infinitive (infinitive without "to"):

be (past)	be (present)	all other verbs (past & present)
I were you were he, she, it were we were you were they were	I be you be he, she, it be we be you be they be	I work you work he, she, it work we work you work they work

The subjunctive does not change according to person (I, you, he etc).

Use of the Subjunctive

We use subjunctives mainly when talking about events that are not certain to happen. For example, we use the subjunctive when talking about events that somebody:

• wants to happen
• anticipates will happen
• imagines happening

Look at these examples:

• The President requests that you be present at the meeting.
• It is vital that you be present at the meeting.
• If you were at the meeting, the President would be happy.

The subjunctive is typically used after two structures:

• the verbs: ask, command, demand, insist, propose, recommend, request, suggest + that
• the expressions: it is desirable, essential, important, necessary, vital + that

Here are some examples with the subjunctive:

• The manager insists that the car park be locked at night.
• The board of directors recommended that he join the company.
• It is essential that we vote as soon as possible.
• It was necessary that every student submit his essay by the weekend.

Notice that in these structures the subjunctive is always the same. It does not matter whether the sentence is past or present. Look at these examples:

• Present: The President requests that they stop the occupation.
• Past: The President requested that they stop the occupation.

• Present: It is essential that she be present.
• Past: It was essential that she be present.

The use of the subjunctive as above is more common in American English than in English, where should + infinitive is often used:

• The manager insists that the car park should be locked at night.
• It was essential that we should vote as soon as possible.

We usually use the subjunctive were instead of "was" after if (and other words with similar meaning). Look at these sentences:

• If I were you, I would ask her.
• Suppose she were here. What would you say?

Why do we say "I were", "he were"?

We sometimes hear things like "if I were you, I would go" or "if he were here, he would tell you". Normally, the past tense of the verb "to be" is: I was, he was. But the if I were you structure does not use the past simple tense of the verb "to be". It uses the past subjunctive of the verb "to be". In the following examples, you can see that we often use the subjunctive form were instead of "was" after:

• if
• as if
• wish
• suppose

Formal (The were form is correct at all times.)	Informal (The was form is possible in informal, familiar conversation.)
If I were younger, I would go.	If I was younger, I would go.
If he weren't so mean, he would buy one for me.	If he wasn't so mean, he would buy one for me.
I wish I weren't so slow!	I wish I wasn't so slow!
I wish it were longer.	I wish it was longer.
It's not as if I were ugly.	It's not as if I was ugly.
She acts as if she were Queen.	She acts as if she was Queen.
If I were you, I should tell her.	Note: We do not normally say "if I was you", even in familiar conversation.

Some fixed expressions use the subjunctive. Here are some examples:

• Long live the King!
• God bless America!
• Heaven forbid!
• Be that as it may, he still wants to see her.
• Come what may, I will never forget you.
• We are all citizens of the world, as it were.

Reference:
http://www.englishclub.com/grammar/verbs-subjunctive.htm