когда ставится was и were в Past progressive?

I was
You were
He/She/It was (the dog was, the man was)
We were
They were (the dogs were, the men were)

Исключение: в условных предложениях всегда пишется were:

If I were you (Если бы я был тобой)
If he were with us (Если бы он был с нами)