Past subjunctive
The past subjunctive has the same form as the past simple tense except in the case of the verb be. Traditionally, the past subjunctive form of be is were for all persons, including the first and third person singular. However, today I/he/she/it was is more common while were is mainly used in formal styles and in the set phrase if I were you.
The past subjunctive is used in subordinate clauses and refers to unreal or improbable present or future situations:
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.)
It's time the kids
were
in bed.
(The kids are not in bed.)
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 probably doesn't.)
Related topics:
Form: past simple
Unreal tenses
Second conditional
Wishes about the present
IT'S (HIGH) TIME
AS IF / AS THOUGH
WOULD RATHER / WOULD SOONER + clause with the past subjunctive
Appendix: irregular verb forms