I WISH I WERE A BIRD.怎么这句子里面用WERE,不用WAS啊?是不是书上写错了

I WISH I WERE A BIRD.怎么这句子里面用WERE,不用WAS啊?是不是书上写错了 为什么是I wish I were a bird 而不是I wish I was a bird If I were a bird的英语语法问题?为什么用were 不用was? I wish I ____(be) a bird.答案是were, am的过去式是was,为什么当表示虚拟语气,我希望我是一只鸟时,要用I wish i were a bird,而不用wa am的过去式是was， 为什么当表示虚拟语气，我希望我是一只鸟时，要用I wish i were a bird，而不用w I wish I were here yesterday中为什么不用was I wish I were a bird or could fly like a bird if i were a bird 为什么 if i were a boy 中的were 不用was? i wish i were a girl.可以换成i was么,为社么 ,社么时候用was啊 How I wish I were a bird and I could fly in the sky