单选题 Questions 22 to 25 are based on the passage you have just heard.
【正确答案】 C
【答案解析】[听力原文]
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. Plaque is me main enemy of healthy teeth. Everyone has plaque, the result is tooth decay and gum disease. Plaque is always forming on the teeth, especially at the gum line. ff plaque is not removed, it builds up and gets under the gum line. 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, which break down the tooth"s harder outer covering. 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. Small pockets form around the teeth. The pockets trap more bacteria and food particles. Finally, the bone supporting the teeth is attacked and starts to shrink. Teeth become loose and may fall out. Adults lose most teeth this way. Keep your mouth healthy. When you brush your teeth, do a good job.

What does the speaker say about our teeth?

[解析] 细节题。文中提到它们是我们身体活着的一部分。也就是C选项所提到的。故本题选C。
【正确答案】 D
【答案解析】[听力原文]
What does the speaker say about plaque?

[解析] 细节题。文中提到,它是牙齿上的一层粘性无色薄膜。同时根据上一句,可知“it”指代的是“plaque”,故选D。其他选项中,要及时拔掉的是坏了的牙齿,所以A选项是错误的;B选项没有提及;因为包含血管和神经的是牙齿,所以C选项错误。
【正确答案】 A
【答案解析】[听力原文]
Why is sugar harmful to teeth?

[解析] 细节题。文中提到,细菌靠糖生存,它们会把糖变成酸性性质,分解牙齿坚固的外层覆盖物,这和A选项是同义表达。故本题选A。
【正确答案】 B
【答案解析】[听力原文]
What causes adults to lose most of their teeth according to the speaker?

[解析] 细节题。文中先提到“the result is tooth decay and gum disease.”接着又提到如果不治疗的话,“Finally, the bone supporting the teeth is attached and atarts to shrink. Teeth become loose and may fall out. Adults lose most teeth this way.”结果就会导致牙齿脱落。故本题选B。