【问】 She has gray请问上面两个句子有什么区别?
 【答】 hair用于指整个头发或毛发时，是集合名词，不能采用复数形式。
 1. He had his hair cut.
 他理了发。
 2. My dog has a good coat of hair. (Palmer)
 我的狗长了一身好毛。
 3. Hormones also affect Jane's hair.
 激素也会影响简的头发。
 但是当hair用于表示一根根(一缕缕)头发时，则是可数名词。
 1. The very hairs of your head are numbered.
 你头上的头发没有几根了。
 2. She found two hairs. (Palmer)
 她找到了两根头发。
 由上面的例子可以看出，名词的复数形式有时候是表示整体一个部分，因此其数量比单数形式少。
 She has grey hair.是指“她满头白发”，而She has grey hairs.则是指“她有几缕白发。”或“她长白头发了”。
 请做下面的英语试题：
 1. Ten years had elapsed，I found she had____.
 A. a little white hair B. much white hair
 C. a few white hair D. a few white hairs(攻读硕士学位研究生入学考试英语试题，81A)
 2. He has seen many barbers human and they to like the job (TOEFL，70.1)
 3. This is an old photograph of me when I____.
 A. have short hairs B. had short hairs
 C. have short hair D. had short hair(攻读硕士学位研究生入学考试英语试题，80B)