The contrary-to-fact present conditional (sometimes referred to as the "second" conditional) is used to refer to a current state or event that is known to be false or improbable. The past subjunctive (or in colloquial English, simply the past tense) must be used:
If she were [colloq. was] at work today, she would know how to deal with this client.
If I were [colloq. was] king, I could have you thrown in the dungeon.
The same structure can be used to refer to a future state or event:
If I won the lottery, I would buy a car.
If he said that to me, I would run away.
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