When a disease of epidemic proportions rips into the populace, scientists immediately get to work, trying to locate the source o

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问题     When a disease of epidemic proportions rips into the populace, scientists immediately get to work, trying to locate the source of the affliction and find ways to combat it. Oftentimes, success is achieved, as medical science is able to isolate the parasite, germ or cell that causes the problem and to find ways to effectively kill or contain it. In the most serious of cases, in which the entire population of a region or country may be at grave risk, it is deemed necessary to protect the entire population through vaccination, so as to safeguard lives and ensure that the disease will not spread.
    The process of vaccination allows the patient’s body to develop immunity to the virus or disease so that, if it is encountered, one can fight it off naturally. To accomplish this, a small weak or dead strain of the disease is actually injected into the patient in a controlled environment, so that his body’s immune system can learn to fight the invader properly. Information on how to penetrate the disease’s defenses is transmitted to all elements of the patient’s immune system in a process that occurs naturally, in which genetic information is passed from cell to cell. This makes sure that, should the patient later come into contact with the real problem, his body is well equipped and trained to deal with it, having already done so before.
    There are dangers inherent in the process, however. On occasion, even the weakened version of the disease contained in the vaccine proves too much for the body to handle, resulting in the immune system succumbing, and, therefore, the patient’s death. Such is the case of the smallpox vaccine, designed to eradicate the smallpox epidemic that nearly wiped out the entire Native American population and killed massive numbers of settlers. Approximately one in 10,000 people who receives the vaccine contracts the smallpox disease from the vaccine itself and dies from it. Thus, if the entire population of the United States were to receive the Smallpox Vaccine today, 3,000 Americans would be left dead.
    Fortunately, the smallpox virus was considered eradicated in the early 1970s, ending the mandatory vaccination of all babies in America. In the event of a reintroduction of the disease, however, mandatory vaccinations may resume, resulting in more unexpected deaths from vaccination.
    The process, which is truly a blessing, may indeed hide some hidden curses.
What does the example of the smallpox vaccine illustrate?

选项 A、The way that vaccines protect people from diseases.
B、The effectiveness of vaccines in eradicating certain diseases.
C、The practical use of a vaccine to control an epidemic disease.
D、The possible negative outcome of administering vaccines.

答案D

解析 属信息推断题。题目中的关键词smallpox vaccine出现在第三段第三、四句:天花疫苗的情况就是这样,该疫苗试图消灭曾几乎使全美土著居民灭绝并造成大量移民死亡的天花传染病却造成了大量接种疫苗者的死亡。事实上,这两句是对上文的举例说明:但是整个接种过程还有隐患。由此可知,选项D正确。选项A与原文内容不符;选项B与此句正相反;选项C不是主要目的。
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