题目内容：

Biting could be worrying

IT makes our fingers look ugly. It’s dirty. It could hurt a lot. But many people just can’t stop doing it: biting their nails.

Up to 45 percent of teenagers in the UK bite their nails, the BBC reported. There are also many famous nail biters, including ex-British Prime Minister Gordon Brown and American singer Britney Spears.

There’s nothing wrong with biting nails to keep them tidy. But it could get out of control.

Some people bite a nail not because it’s too long, but because they are driving, reading, feeling stressed out, or just have nothing else to do.

The same could happen to skin picking and hair pulling. A normal behavior could become “pathological”(病态的), as experts say.

In 2013, the American Psychiatric Association labeled (把……列为) nail biting as an obsessive-compulsive disorder (OCD). People with this disorder may wash their hands too many times or have to line up their shoes in a certain way.

These behaviors have a lot in common. OCD is doing something normal and healthy too much, NPR reported.

But nail biting is different from other OCD behaviors in at least one way.

“In OCD, the behavior is really unwanted,” Carol Mathews, a psychiatrist（精神病医生）at the University of California, San Francisco, told NPR. People with OCD don’t want to wash their hands over and over again. There is no fun in it. They just fear that if they don’t do something, something else that’s very bad will happen to them.

But nail biters enjoy it.

“It’s rewarding. When you get the right nail, it feels good,” said Mathews.

Therefore some people argue that most nail biters are not having a problem as serious as a mental (心理的) disorder.

But anyway, it’s still a bad habit. So what can we do to stop it?

Since most people bite nails as a way of relieving (缓解) stress, finding another way to relieve that stress could be useful, suggested Rochelle Torgerson, a doctor at the Mayo Clinic in the US. Try playing with your pen instead.

Besides, nail biters feel the urge (刺激，冲动) to bite if they find a small imperfect part of the nail, said Mathews. So always keep your nails in good shape.

1.What does the phrase obsessive-compulsive disorder in Paragraph 6 mean?

A. An activity that people enjoy doing it.

B. A kind of behavior that people is really wanted.

C. A way of doing something that people does it normal and healthy.

D. A mental disorder that people are unable to control the thoughts or the activities.

2.How is nail biting different from other OCD behaviors?

A. People do it over and over again.

B. People do it happily and willingly.

C. It does no harm to people’s health.

D. It is a physical and mental problem.

3.What do doctors suggest people do to stop nail biting?

A. Pick skin or pull hair instead.

B. Force them to control the urge to bite.

C. Keep them busy and forget about nails.

D. Find some other ways to release their stress.