hair用作不可数时用is。hair这个词既可以是可数名词，也可以是不可数名词。hair作为不可数名词是“头发”的总称，是集合名词。例句：I’ll have my hair cut.我要去理发。hair作为可数名词，是指一根一根的“头发”或“毛发”。例句：Look at this，a hair in my soup.看这个，我汤里有根头发。

hair：英[heə(r)]；美[her]

n.汗毛，毛发，（尤指）头发；（动物的）毛，茸毛；毛状物，发毛织物；（植物叶茎上的）茸毛；些微，一点儿；&lt；俚&gt；（计）复杂性；&lt；废&gt；性质，特性

adj.毛发的，用毛发制的，保护毛发的

v.产生（或生长）毛发；形成毛状纤维；去除…的毛发

1、He still has a good head of hair.

他的头发依然很多。

2、Good Lord,what have you done to your hair!

天啊，你把头发弄成什么样子啦！

3、I like the way you've done your hair.

我喜欢你梳的发式。

4、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。

5、Did she use to have long hair?

她过去留长发吗？

6、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。

7、Did you see the length of his hair?

你看见他头发有多长吗？

8、Your hair could do with a cut.

你该理发了。

9、I think grey hair makes you look very distinguished.

我认为灰白的头发使你看上去很有尊严。

10、I must get my hair cut.

我得理发了。

11、He's had his hair cut really short.

他头发理得真短。

12、My hair soon grew back to its natural colour.

我的头发很快又恢复了本色。

13、He parts his hair in the middle.

他梳着中分头。

14、My hair gets full of static when I brush it.

我梳头时头发就有好多静电。

15、Theirs are the children with very fair hair.

他们的孩子是那些长着满头金发的。

16、Have you thought about having your hair in a shorter style?

你有没有想过剪个短发型？

17、Her hair could have done with a wash.

她的头发该洗一洗了。

18、I want about an inch off the back of my hair.

我想把脑后的头发剪短约一英寸。

19、Regular use of conditioner is supposed to give your hair more body.

经常使用护发素能使头发更浓密。

20、Use conditioner regularly to make your hair soft and manageable.

经常使用护发剂来使你的头发柔软而且易于梳理。