阅读短文，回答 47～50 题：
C
One of the greatest killers in the Western world is heart disease. The death rate (率) from the disease has been increasing at an alarming speed for the past thirty years. Medical experts know that people can reduce their chances of getting heart disease by exercising regularly, by not smoking，by changing their diets, and by paying more attention to reducing stress (压力) in their work.
However, Western health-care systems are still not paying enough attention to the prevention of the disease. There is a need for more programs to educate the public about the causes and prevention of heart disease. Instead of supporting such programs，however，the U. S. health-care system is spending large sums of money on the surgical (外科的) treatment of the disease after it develops. This emphasis (强调) on treatment clearly has something to do with the technological advances that have taken in the past ten to fifteen years. In this time, modern technology has enabled doctors to develop new surgical techniques. Many operation that were considered impossible or too risky (有风险的) a few years ago are now performed every day in U. S. hospitals. The result has been a huge increase in heart surgery.
Although there is no doubt that heart surgery can help a large number of people, some people point out that the emphasis on the surgical treatment of the disease has three clear disadvantages.
First, it attracts interest and money away from the question of prevention. Second, it causes the costs of general hospital care to rise. After hospitals buy the expensive equipment that is necessary for modern heart surgery, they must try to recover the money they have spent. To do this, they raise costs for all their patients, not just those patients whose treatment requires the equipment. The third disadvantage is that doctors are encouraged to perform. surgery--even on patients for whom an operation is unnecessary--because the equipment and expert skills are there. A government official recently stated that major heart surgery was often performed even though its chances of success were low. In one type of heart surgery，for example ,only 15 percent of patients improved their conditions after the surgery. However, more than 100,000 of these operations are performed in the United States every year.
第 47 题 What effect has modern technology had on medicine？