2. 外语
  3. The record of the past half century has established, I think, the two general principles about human disease. First, it is neces

The record of the past half century has established, I think, the two general principles about human disease. First, it is neces

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问题     The record of the past half century has established, I think, the two general principles about human disease. First, it is necessary to know a great deal about underlying mechanisms before one can really act effectively; one had to know that the pneumococcus (肺炎球菌) causes lobar pneumonia (球形肺炎) before one could begin thinking about antibiotics.
    Second, for every disease there is a single key mechanism that dominates all the others. If one can find it, and think one’s way around it, one can control the disorder. This generalization is harder to prove and arguable—it is more like a strong hunch (直觉) than a scientific assertion— but I believe that the record thus far tends to support it. The most complicated, multicell, multi-tissue, and multiorgan diseases I know are tertiary syphilis, chronic tuberculosis, and pernicious anemia. In each, there are at least five major organs and tissues involved, and each appears to be affected by a variety of environmental influences. Before they came under scientific appraisal, each was what we now call a "multifactorial disease. " And yet, When all the necessary facts were in it was clear that by simply switching off one thing—the spirochete, the tubercle bacillus, or a single vitamin deficiency—the whole array of disordered and seemingly unrelated pathological mechanisms could be switched off, at once.
What is the main idea of the passage?
选项 A、Scientific appraisal shows that multifactorial diseases are often due in part to environmental conditions.
B、In the past half century, scientists have been able to find only a few principles that apply to all diseases.
C、Each disease has single underlying mechanism that must be understood before the disease can be cured.
D、Many diseases that were once life-threatening can now be cured by antibiotics.
答案B
解析 文中第一句为主题句，开门见山地点明了文章的主题：“我认为，过去的半个世纪的记录已经确立了两条有关人类疾病的普遍原则。”此后的内容均是对这两条原则的进一步阐述，所以选项B正确。A“科学的评价说明，多重因素造成的疾病的病因通常是部分由于环境条件的影响”。这句话只是对第二条原则的阐发，并不是文章的主题。C“每种疾病都有单独的内在机理，因此在治疗疾病之前必须先弄清这种机理”。这只是文中提到的第一条原则，也不是文章的主题。D“曾经对生命构成威胁的许多疾病现在都能用抗生素治愈”，文中并未提及。
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