【正确答案】 A

【答案解析】[听力原文] 11-13
Take care of your teeth and your teeth will take care of you. Your teeth are a living part of your body. They have nerves and blood vessels. Diseased teeth can cause pain, die, and fall out. False teeth often do not work as well as nature teeth. If you do take proper care of your teeth, you can keep them your entire life.
Plaque is the main enemy of healthy teeth. Everyone has plaque which is always forming on the teeth. Plaque that is left on the teeth for some time hardens. The result is tooth decay and gum disease.
The bacteria in plaque live in sugar turned into acids. If left untreated, decay goes deeper and deeper into the tooth. After a while the decay reached the nerves and blood vessels of the inner tooth. By the time this happens, the tooth has probably started to ache.
In addition to tooth decay, there are also gum diseases to watch out for. The bacteria in plaque make poisons that attack the gums. Teeth become loose and may fall out. Adults lose most teeth this way.
Gum disease starts slowly. There may be no pain. As a rule, gum disease first appears as swelling. Then the gums become tender. There also may be bleeding. To heal diseased gums, your teeth need one or more dental cleanings. Regular visits to your dentist are a must.
Many people worry about bad teeth. This may result from several causes. It may be caused by plaque. Decayed teeth can cause bad breath.
Keep your mouth healthy! When you brush your teeth, do a good job.
[解析] 本题为细节题。从文章“Your teeth are a living part of your body. They have nerves and blood vessels.”可得知答案。