Section B
Passage One
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 natural 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. It is a sticky, colorless film that coats the teeth. Plaque 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 on sugar. They change sugar into acids. If left untreated, decay goes deeper and deeper into the tooth. After a while the decay reaches 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 could be due to gum disease or leftover bits of food. 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.
Questions 26 to 28 are based on the passage you have just heard.
26. What does tooth contain according to the passage?
【解析】選[A]。根據(jù)文中的Your teeth are a living part of your body. They have nerves and blood vessels可知，牙齒存在神經(jīng)和血管，由此可知選項[A]正確。
27. What does the bacteria in plaque live on?
【解析】選[C]。文中提到The bacteria in plaque live on sugar，由此可知，牙菌斑里的細菌依靠糖分生存，因此選項[C]正確。
28. What is the most appropriate title for this article?
【解析】選[B]。本文通過介紹牙齒的構(gòu)成部分以及牙菌斑引發(fā)的蛀牙和牙齦疾病，指出保持牙齒健康的必要性，因此適合本文的標(biāo)題應(yīng)為：蛀牙和牙齦疾病，[B]項正確。
Passage One
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 natural 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. It is a sticky, colorless film that coats the teeth. Plaque 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 on sugar. They change sugar into acids. If left untreated, decay goes deeper and deeper into the tooth. After a while the decay reaches 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 could be due to gum disease or leftover bits of food. 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.
Questions 26 to 28 are based on the passage you have just heard.
26. What does tooth contain according to the passage?
【解析】選[A]。根據(jù)文中的Your teeth are a living part of your body. They have nerves and blood vessels可知，牙齒存在神經(jīng)和血管，由此可知選項[A]正確。
27. What does the bacteria in plaque live on?
【解析】選[C]。文中提到The bacteria in plaque live on sugar，由此可知，牙菌斑里的細菌依靠糖分生存，因此選項[C]正確。
28. What is the most appropriate title for this article?
【解析】選[B]。本文通過介紹牙齒的構(gòu)成部分以及牙菌斑引發(fā)的蛀牙和牙齦疾病，指出保持牙齒健康的必要性，因此適合本文的標(biāo)題應(yīng)為：蛀牙和牙齦疾病，[B]項正確。