Which of the following most logically completes the passage?
Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ______.
the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis
every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis
Answer: B
Why not C? Thank you.作者: meckychen 时间: 2010-1-8 09:20
Can anyone help me?作者: prayer 时间: 2010-1-8 10:24
这道题需要抓住题目中的关键词：第一个是fatal，说阑尾炎是致命的；第二个关键词是 misdiagnoses，也就是说存在一定概率会出现错误，可能有阑尾炎的被诊断为不需要做，或者不需要做手术的给诊断为需要做。结合这两个关键词，得出，只有存在不需要做手术的给诊断为需要做手术的 misdiagnose才是可以接受的，否则就是fatal的，因为就算做了手术也是low-risk的，但是反过来需要做手术的阑尾炎给诊断出不需要做就要死人的。 所以，综合上面的信息，得出这个仪器必须满足 misdiagnose是不需要做手术的给诊断为需要做手术的误诊，毕竟2%也不是很多，相对于以前的20%少多了。也就是答案B说的。 答案C说诊断有的的确有，那么诊断为没有的呢？可没说真的没有啊，要是误诊就要死人啦作者: meckychen 时间: 2010-1-9 11:18
thanks