For several years, scientists have been testing a substance called interferon (干扰素), 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 of 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 powerful 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 Karolinska Institute, has treated more than one hundred cancer patients with the new drug. Among a group of selected patients who has undergone surgical procedures for advanced cancer, 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 have 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.
单选题
In what does interferon differ from antibiotics? 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 effective, while interferon is not. D. Antibiotics kill germs by attacking them directly, while interferon does not.
【正确答案】
D
【答案解析】[解析] 推断型题。本题的解题点在第3段。文章第一句话提到“Unlike antibiotics． interferon does not attack germs directly，”也就是说，与抗生素不同的是，干扰素不直接攻 击细胞。所以正确答案是D选项。
单选题
What effect does interferon have on infection? A. It provokes a negative reaction. B. It keeps healthy cells from becoming infected. C. It causes healthy cells to grow. D. It attacks viruses.
【正确答案】
B
【答案解析】[解析] 细节题。解题点在第3段第2句。文章提到“Instead，it makes unaffected cells resistant to infection，and prevents the multiplication of viruses within cells．”其意思是，干 扰素的作用是让未干扰的细胞具有抗感染性。unaffected cells和healthy cells表达同样的 意思，所以正确答案是B选项。
单选题
Interferon is produced by ______ A. infecting viruses, bacteria, and tumors with a drug B. infecting proteins with a virus C. infecting white blood cells with a virus D. infecting viruses with proteins
【正确答案】
C
【答案解析】[解析] 细节题，问干扰素是如何产生的。由第2段倒数第2句“The drug is produced by infecting white blood cells with a virus，”可知正确答案是C选项。
单选题
Interferon has not been widely used because it is ______ A. still very dangerous B. not yet available in the United States C. difficult to produce in large quantities D. not effective for human beings
【正确答案】
B
【答案解析】[解析] 推理题。解题点在最后一段。文章最后提到“a large-scale project supported by the American Cancer Society is now underway．Ifthe experiment is successful，…”由此可知，该药 在美国尚在试验当中。既然是试验，自然就不可能大范围内使用了。所以正确答案是B选项。 其他选项均可以在原文中找到相应的信息点，如A选项，文中未提到该药是危险的；C选项， 文中没有说干扰素难以大量生产；D选项，瑞典的试验表明，与常规治疗方法相比，干扰素 的治疗效果是明显的，故D项不对。
单选题
Which of the following is true of the results of Dr. Strander's experiments? A. Both interferon and conventional treatments should be used to ensure the survival of the patients. B. At the end of three years, only ten to thirty percent of the patients who had not received interferon died. C. Only the patients who received interferon survived. D. Most of the patients who were treated with interferon survived.
【正确答案】
D
【答案解析】[解析] 推理题。本题的解题思路同29题。由上题中D项的分析，及原文提及的“The survial rate over a three-year period was 70 percent among those…”可知，使用干扰素治疗的大 部分患者存活了。所以正确答案是D选项。