In addition to verb tenses, which indicate time, there are verb moods which indicate a state of being. The most common moods are the interrogative (for questions), the indicative (for statements), the conditional (for ‘if’ sentences) and the subjunctive. The subjunctive mood conveys ideas that are not facts, for example wishes or imaginary situations.
Uses of the subjunctive

1. Wishes
   (lives changes to live)
   Long live the King!
   God bless you!
   May you recover soon!
   Long may the queen reign over us!
   
   
2. Unfulfilled or impossible conditionals
   (be changes to were)
   If the police were here, we would all feel safer.
   If I were a man, I would go off around the world with my rucksack.
   
   
3. After verbs suggest and propose (with or without an auxiliary verb or with should), is changes to be or should be.
   I propose the meeting be/should be postponed.
   I suggest he be/should be reprimanded.
   
   
4. After impersonal constructions to express wishes and suppositions
   Here the subjunctive looks like a past simple (unless it is the verb to be) but isn’t.
   I wish I had more money.
   I wish he were here now.
   If only I had more time to revise for my exams.
   It is time we went home.
   If only you weren’t so stubborn.
   I would rather you made the decision.
   
   
5. After may or might to indicate purpose or hypothesis
   The teacher gave up her free time in order that she might prepare her pupils for the exam.
   However rich a person may be, he is never satisfied.
   Whatever may be the result of your test, I know you have done your best.
   Try as I might, I could not reach the top.