虚拟中“was” 和 were 只能用 “were” .
If I were you I would……（强调将要）
I am not you,so I can’t make the decision.
If I were you,I could make the decision.
I am not a bird,so I can’t fly to you right away.
If I were a bird I could fly to you right away.
I don’t know his phone number,so I won’t ring him up.
If I knew his phone number,I would ring him up.
He isn’t free at the moment,so he won’t go to the cinema.
If he were free at the moment,he would go to the cinema.
“How should the city be run?”
“If I were a mayor,I would make the streets cleaner and hire more policemen.”
If I could rearrage the alphabet,I would put U and I together.