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 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 .

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis (B)

E. 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

我选C, 答案是B. 百思不得其解!

请教NN们~~~~

自己再想想,好象有点眉目了:

B的意思是说这2%的误诊率都是实-测+(实际没有但测试有),也就是说,实+测-(实际有但测试没有)的情况为零,从而解释了为什么doctors can largely avoid unnecessary removals of the appendix(与以前相比只剩2%,大大减少了) without, however, performing any fewer necessary ones than before(一例都没有了).

不过真到考试时哪有那么多时间去分析啊,郁闷!

解释题。

没2楼那么复杂

B说新手段误诊的都是那些实际上没得病的，就是说，误诊＝没病，既然没病，当然不需要手术－－－>不必要的手术减少了，而必要的手术没变（avoid unnecessary removals of the appendix without performing any fewer necessary ones than before）

这题我做时硬是没看懂，花了5分钟猜了个E，MD，明天不干这种事情了。

b应该是说误诊都是把实际上没阑尾炎的诊断成了阑尾炎，这就说明真正有阑尾炎需要做手术的不会被漏掉.