Subjunctive Mood
I. Unreal Conditionals: 
1.    Verb Forms:
a.    contrary to past events: if (had done), (would have done);
b.    contrary to present events: if (were or did), (would do);
c.    contrary to future events: if (were to do or should do or did), (would do).
e.g. If I had left a little earlier, I would have caught the train.
If I were you, I would reconsider their proposal.
If it were to rain (should rain,rained) tomorrow, what would we do?
2.    Mixed unreal conditionals:
e.g. If you had attended the meeting yesterday, you would know what to do now.
If we had set out a little earlier, we would not be walking in the rain now.
3.    Implied unreal conditionals: (without, but for, or, otherwise, but that)
But for (Without) your help, I would not have finished the work in time.
I used a computer; otherwise, it would have taken me much longer to complete the job.
But that you helped him, he would not have succeeded.
4.    Inversion: (had,should,were)
Were I you, I would do it in another way.
Had it not been for your help, I would not have finished it in time.
Should it rain tomorrow, the football match would be cancelled.
II. Bare infinitive in the noun clauses:
1.    order that- (order, command, demand, request, require, ask, suggest, advise, recommend, propose, insist, move, decide, determine, resolve, decree, desire): object clauses.
e.g. She demanded that the meeting be put off.
2.    It is ordered that-: (the verbs are the same with 1): subject clauses.
It is suggested that the football match be postponed.
3.    It is necessary (of necessity) that-: (necessary, essential, imperative, desirable, important, natural, urgent, preferable, advisable, significant): subject clauses.
It is necessary (of much necessity) that every student study English grammar well.
4.    I think it necessary (of much necessity) that every student take notes in class.
5.    The suggestion is that-: (suggestion, proposal, advice, recommendation, desire, order, motion, request, requirement, preferrance, etc.): predicative clauses.
Her suggestion is that he go to see the dean at once.
6.    the suggestion that- (appositive clauses)
We disapprove of the proposal that she go out alone at night.(appositive clause)
………………………………..that she has put forward at the meeting.(attributive clause)
III. Subjunctive in some other clauses:
1.    wish, if only:
I wish I were a bird . I wish I had not told her the news. I wish it would snow tomorrow.
If only I had not said that. (the verb forms are the same with those in the object clauses after WISH).
2.    would, would rather, would sooner, would just as soon+that-
I would that you had posted the letter yesterday.
……………you posted t5he letter right now.
I would that you bought (would buy) the house next year.
3.    It is time (high time, about time) that we went home.
4.    as if, as though:
She often speaks to her husband as if she were his mother..
She behaved herself as though she had known nothing about it’
5.    lest, for fear that:
I hid the book safely for fear that she (should) find it.
6. He is my best friend, my second self, as it were.
7.Bring the umbrella with you in case it should rain (rains).
IV. Be-type subjunctive:
Whatever be his defense, we cannot tolerate this disloyalty.
Whether she be right or wrong, she will have my unswerving support.
So be it then.
Far be it from me to spoil the fun.
Home is home, be it ever so homely.
The leisure activities, be it TV-watching or bird-watching, are beneficial to peopleˊs health.
Be that as it may, our expenditure is bound to increase.
If need be, we can always bring another car.
Be it understood that our foreign policy remains unchanged.

The Differences between IF and WHETHER:
Whether (If*) she comes or not does not concern me.(Stared ones are wrong uses.)
The question of whether (if*) the animal is male or female is not important.
My question is whether (if*) she really loves her boyfriend.
My original doubt, whether (if*) she killed her boyfriend or not, has not yet been removed.
The leisure activities, whether (if*) it is TV-watching or bird watching, are good for our health.
I do not care whether (if) it rains or not.
…………….whether or not your car breaks down.
…………….if or not* ……………………………
…………….if it does not rain.
…………….whether it does not rain*.
Note:1. We cannot use IF to draw forth the subject clause, object clause of prep., predicative clause, appositive clause, and adverbial clause of concession.
2. if or not cannot be used closely together, and the verb in the WHETHER clause cannot take a negative form.

          The Differences between if…… not and unless:
1. if……not cannot be replaced by unless when it is used in unreal conditionals:
  If she were not so silly, she would understand.
2. In unless clause, we may use negative word, but we cannot use negatives in the if…not clause:
  I will go unless no one else does.
  I will go if no one else does not*.
3. In if………not, we can use non-assertive words such as any-compounds, ever, yet, any more, any longer, either, at all, but in unless clause, we usually use assertives:
  I will be very angry if you have not spoken to her yet.
  I will be very angry unless you have already spoken to her.
  ……………………unless you have spoken to her yet*.