[英语课]

I cut my hair yesterday, and the hairdresser said that I got some white hairs or grey hairs. It's true, I find that I have more white hairs recently.

hair 是一个不可数名词 (uncountable noun), 所不用复数。如：
    My hair is short and straight.

但是在说到头发中有白头发或别的不一样时，就用复数 hairs, 所以是 white hairs.
  如： Though he is very young, he has many white hairs ( grey hairs) already.