头发是不可数名词。hair：n.(尤指)头发;毛发;有…毛发(或头发)的;(植物叶茎上的)茸毛。复数： hairs
相关介绍：
What a difference! You look great with your hair like that.
真是判若两人！你梳这种发型显得太帅了。
Did she use to have long hair?
她过去留长发吗？
Mary's red hair always made her conspicuous at school.
玛丽的红头发在学校里总是很惹眼。
Did you see the length of his hair?
你看见他头发有多长吗？
Your hair could do with a cut.
你该理发了。
