The past subjunctive has the same form as the simple past, except in the case of the verbA part of speech that expresses an action or a state. E.g.: John seldom plays tennis. be, the past subjunctive form of which is either I/he/she/it was or I/he/she/it were. Were is more common in certain set phrases (if I were you) and in expressionA word or group of words used in a particular situation. E.g.: Good morning, at six, on the sofas of unrealA tense that expresses a hypothetical situation. E.g.: I wish you were here.ity, while was is more often used in spoken language. 

The past subjunctive is used in subordinate clauseA clause that cannot be a sentence in itself. It is joined with a main clause. E.g.: I wouldn’t go there if I were you. ("if I were you") When I arrived he was surfing. ("when I arrived")s and expresses an unreal or improbable present situation. 

If I were you, I would apply right now. (I am not you.)
What would you do if you won the lottery? (You probably won't win the lottery.)
I wish you were here. (You are not here.)
I'd rather your boyfriend stopped calling you in the middle of the night. (Your boyfriend keeps calling you.)
He looks as if he knew the answer. (He gives the impression that he knows the answer, but he doesn't.) 

Past perfect subjunctive
The subjunctive Present subjunctive