◆29.A. Coca Cola.
B. Sausage.
C. Milk.
D. Fried chicken.
◆30.A. He has had thirteen decayed teeth.
B. He doesn't have a single decayed tooth.
C. He has fewer decayed teeth than other people of his age.
D. He never had a single tooth pulled out before he was fifty.
◆31.A. Brush your teeth right before you go to bed in the evening.
B. Have as few of your teeth pulled out as possible.
C. Have your teeth X-rayed at regular intervals.
D. Clean your teeth shortly after eating.
听力原文：
How many teeth have you had filled in the past twoyears? If you follow the advice of Dr. Faustick, youmay be able to reduce the number of your visits to adentist. Dr. Faustick conducted a two-year surveyto find out how to prevent or reduce dental decay. 946 students took part in the experiment. 523students cleaned their teeth within ten minutes ofeating. When possible, they used a toothbrush; when this was impossible, they washed theirmouth thoroughly with water. The remaining 423 students merely cleaned their teeth whenthey went to bed and when they got up in the morning. All the students had their teeth X-rayed at the end of the first and second years. At the end of the first year, the night andmorning group had three times as many decayed teeth as the clean-after-each-meal group. Atthe end of the second year, the latter group had 53 percent fewer decayed teeth than theformer group. Dr. Faustick has cleaned his teeth after every meal for thirteen years and [30]hasnot had a single decayed tooth. He pointed out that [29]sugar is a major agent in dentaldecay, particularly the sugar in sweets, cakes, and soft drinks. [31]Ideally you should keep atoothbrush in your pocket and use it immediately after you have finished eating. When this isimpractical, you can at least make sure that you have a drink of water and let the waterthrough your teeth to force out any particles of food. 7 out of 10 people lose at least half theirteeth by the time they are fifty. Many have a complete set of false teeth by that time. In anycase, neither toothache nor a visit to a dentist is very pleasant. So it is worthwhile making aneffort to keep your own teeth as long as possible. The main preventative agent is simply water.
参考答案
Questions 29 to 31 are based on the passage you have just heard.
29. According to the passage, what type of food or drink is most likely to cause dentaldecay?
正确答案：A
解析：短文提到，糖是造成蛀牙的元凶，尤其是糖果、蛋糕和软饮料中的糖分。在四个选项中，只有可口可乐符合题意。所以答案为A。
30. What does the passage tell us about the condition of Dr. Faustick's teeth?
正确答案：B
解析：短文提到，Dr. Faustick没有一颗蛀牙(has not had a single decayed tooth)。由此可知选B。
31. What does Dr. Faustick suggest to prevent dental decay?
正确答案：D
解析：短文提到，理想的做法是，你应该随身携带牙刷，吃完东西马上刷牙。由此可知Dr. Faustick的建议是吃完饭立刻刷牙，所以答案为D。
