【正确答案】 D

【答案解析】[听力原文] Millions of dollars are spent every year in fighting tooth decay. Despite better education and a higher standard of living, the number of people needing dental treatment increases every year. A British dentist, Mr. R.V. Tait, has thought about why this is the case, and has made some suggestions about what could be done to improve the situation. He has pointed out that our thirty-two teeth evolved in the past to deal with a much tougher diet than we have now. Our ancestors ate tough gritty food, and so they needed many teeth. Our teeth, however, do not have to cope with such a diet, because we eat much softer food. Unless, therefore, we are prepared to eat the diet of our ancestors, we should get rid of some of our teeth. Instead of thirty-two teeth, it would be better if we had a well-spaced set of twenty to twenty-four. This would force the rest to work harder and make them healthier. Another advantage would be that with larger spaces between our teeth, tooth decay could not develop, as it does now, between teeth that are very close together. Furthermore, most extractions would be done during childhood when teeth can be extracted easily, and sockets heal with little pain. Mr. Tait's theory is original and convincing. Yet it is a remarkable piece of work, because most dentists believe we should keep as many of our teeth as possible. It is unlikely that they will be persuaded by his ideas. According to Mr. Tait, what should we do to improve the situation of tooth decay?