请教虚拟语气的一个问题

Superyekai

虚拟语气的一个例子：If I were you, I woud not let her go.

请问从句的系动词可以用was吗，还是be动词的虚拟形式只能够是were？

另外有没有牛牛总结过虚拟语气的用法。

谢谢

andrew_li

Both "was" and "were" are correct in this case.