不知道你是不是问either后的名词?常用单数.它的意思是“两者中任一的,非此即彼"
You can stand on either end of the boat if you keep still.
Which book do you want,this or that?
Either (book) is OK.
Either of 后面的名词一般就是用两个了.
Either of the (two) books is/are good.
either做限定词时后面被修饰的复数名词一定要数量是2的吗?