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题库 / GMATLA-CR-73
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
原来的20%-->不该手术的(unnecessary)都去手术了
而新方法的2%-->100个中仅2个误诊-->所以可以largely减少unnecessary的，同时不会减少necessary的
意思就是这减少的18%中全都是减少unnecessary的，而不会影响necessary的
而B的意思是，误诊的2%全都是把没病当作有病，那么这个仍然是属于”不该手术的(unnecessary)都去手术了“，说明没有影响到”该做手术的却没做“这个范围里，也就是不会减少necessary的
感觉这道题主要是对doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer 【necessary】 "ones" than before的理解
这里的ones指代的是前面的surgery，就是说该切的都切了，切错的也是没得阑尾炎的，也就是大大避免了误切事件。
如果有一个是有阑尾炎但是被诊断为没问题，那就是少切了，那就是跟without performing any fewer necessary ones相违背的，所以被误诊的必须是把没问题的看出了有问题的，选B: the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, [in fact], have it
（这个句子中的“in fact”是状语插入语修饰does not have it）
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