a. He must be very old. Look，he has grey ________.
b. He found some ________ in his soup.
A. hair，hair B. hairs，hairs C. hair，hairs D. hairs，hair
此题应选 C，容易误选 A，误认为hair永远不可数。其实hair这个词既可以是可数名词，也可以是不可数名词，只是含义稍有变化：
Look at this, a hair in my soup. 你瞧，我的汤里有根头发。
The cat has left her loose hairs all over my clothes. 猫掉的毛弄得我衣服上到处都是。
My father has quite a few gray hairs. 我父亲已有不少白发。
There is not a gray hair on his head. 他头上没有一根白头发。
I’ll have my hair cut. 我要去理发。
He has blond hair. 他有一头金发。
She has a beautiful head of hair. 她有一头漂亮的头发。
The woman likes to do her hair in foreign style. 这个女人喜欢把头发梳成外国式。
He has grey hair. 他满头白发。
He has grey hairs. 他有些白发了。