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  3. For several years, scientists have been testing a substance called interferon, a potential wonder drug that is proving to be eff

For several years, scientists have been testing a substance called interferon, a potential wonder drug that is proving to be eff

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问题     For several years, scientists have been testing a substance called interferon, a potential wonder drug that is proving to be effective in treating a variety of ailments, including virus infections, bacteria infections, and tumors. To date, the new drug has provoked no negative reaction of sufficient significance to discourage its use. But in spite of its success, last year only one gram was produced in the entire world.
    The reason for the scarcity lies in the structure of interferon. A species specific protein, the interferon produced from one animal species cannot be used in treating another animal species. In other words, to treat human beings, only interferon produced by human beings may be used. The drug is produced by infecting white blood cells with a virus. Fortunately, it is so potent that the amount given each patient per injection is very small.
    Unlike antibiotics, interferon does not attack germs directly. Instead, it makes unaffected cells resistant to infection, and prevents the multiplication of viruses within cells.
    As you might conclude, one of the most dramatic uses of interferon has been in the treatment of cancer. Dr. Hans Strander, research physician at Sweden’s famous Karohnska Institute, has treated more than one hundred cancer patients with the new drug. Among a group of selected patients who had undergone surgical procedures for advanced cancer, half were given conventional treatments and the other half were given interferon. The survival rate over a three-year period was 70 percent among those who were treated with interferon as compared with only 10 to 30 percent among those who had received the conventional treatments.
    In the United States, a large-scale project supported by the American Cancer Society is now underway. If the experiment is successful, interferon could become one of the greatest medical discoveries of our time.
In what does interferon differ from antibiotics?
选项 A、Interferon has serious side effects, whereas antibiotics do not.
B、Interferon is available in large supply, whereas antibiotics are not.
C、Antibiotics are very potent, while interferon is not.
D、Antibiotics kill germs by attacking them directly, while interferon does not.
答案D
解析 文中第三段第一句说：“与抗生素不同，干扰素并不直接进攻细菌。”由此我们可以推断出，抗生素是直接进攻细菌进而杀死它们，而干扰素却不是。因此选项D正确。本题亦可以通过排除法找到答案。选项A“干扰素有严重的副作用，而抗生素却没有”与文中内容不符。第一段第二句说：“截止到目前，这种新药还没有因为副作用明显而引起人们的抵制。”由此选项A可排除。选项B“干扰素有大量的供给来源，而抗生素却没有”。文中第一段最后一句说：“但是，尽管它获得了成功，全世界去年却只生产了1克。”文中第二段又对干扰素的缺乏原因作了解释。由此选项B可排除。选项C“抗生素是有效的，而干扰素却不是”。在文中第一段第一句中说：“……一种有可能成为特效药的药物已经被证明在治疗各种疾病方面是有效的……”。由此，选项C可排除。
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