gwd-21-4, B?

21-Q4 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

however 用在那里挺别扭？？

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GWD 21-33

One of the limiting factors in human physical performance is the amount of oxygen that is absorbed by the muscles from the bloodstream. Accordingly, entrepreneurs have begun selling at gymnasiums and health clubs bottles of drinking water, labeled “SuperOXY,” that has extra oxygen dissolved in the water. Such water would be useless in improving physical performance, however, since the only way to get oxygen into the bloodstream so that it can be absorbed bye the muscles is through the lungs.

Which of the following, if true, would serve the same function in the argument as the statement in boldface?

A.     the water lost in exercising can be replaced with ordinary tap water

B.     the amount of oxygen in the blood of people who are exercising is already more than the muscle can absorb

C.     world-class athletes turn in record performance without such water

D.     frequent physical exercise increases the body’s ability to take in and use oxygen (A)

E,lack of oxygen is not the only factor limiting human physical performance

I think the right key shoud be B rather A?

21-4 题中说unnecessary removals比率为20%

B是说2%的misdiagnoses是把原来没有阑尾炎的诊断成有阑尾炎的，所以unnecessary removals的就是这2%的人

所以largely avoid unnecessary removals of the appendix

但是这样的话就增加风险-2%本来没有阑尾炎的也去做手术了

题目中20%人是本来就有阑尾炎的-只是这些人是不用做手术的阑尾炎，

这里是否把没有阑尾炎的人看成是有阑尾炎但不用做手术的人看成是同类人？所以只要降低这类人不必要的手术就可以了？

我选了C,原文的意思是这种新的内窥探测准确率很高,因此用这种方式可以大量地避免不必要的误切除,而且相对以前来说也不会少切除真正有病的阑尾.

B的意思说用这种方式的误诊就是会遗漏真正有阑尾炎的人,不能满足原文的意思阿,为什么选它?

C的意思是说用这种方式把有病的阑尾都切了,也就是该切的都切了,就不会造成"不必要的切除"和"漏切",意思很好阿,为什么不对?

下文的病就是阑尾炎啦。

题目：老方法诊断出得病的有20%未得。新方法只有2%误诊率。因此使用新方法可以在不减少必要的手术的情况下，避免不必要的手术。

解释：那2%往往是诊断没得病，实际得了病。

那么，假设有100人，a1,a2...~a80均真病了，b81,b82~b100是健康的。

按照老方法，可能将这100人全部诊断为生病，一并送去咔嚓了，那么误诊率20%，b81,b82~b100无辜受害。

按照新方法，将a1,a2,...~a78诊断为生病，a79,a80,b81,b82~b100诊断为健康。B说其中只有a79,a80属于误诊，也应送去咔嚓。那么新方法就没有减少必要的手术，同时完全避免了不必要的手术。

C是说所有被诊断为生病的人真的病了。也就是说前78个人全病了。这只能说明完全避免了不必要的手术，不能说明没有减少必要的手术。因为a79,a80的手术必要，却减少了。

vote for B  但是，uibewsj，我认为你对B选项的分析有问题

文章的要求有两个：

1.largely avoid unnecessary removals of the appendix

2.without performing any fewer necessary ones than before

B新方法2%的误诊是将实际未生病的人诊断为生病，换句话说就是实际生病的人一个都不会漏掉，符合without performing any fewer necessary ones than before的要求，同时由于未生病的人诊断为生病的比例只有2%，大大低于原来的20%，因此符合largely avoid unnecessary removals of the appendix

C新方法诊断为有病的实际上都有病，这符合largely avoid unnecessary removals of the appendix ，但是新方法诊断为没病的是不是都没病呢，选项没有交代，因此无法判断是否符合without performing any fewer necessary ones than before（如果新方法诊断为没病的实际上有病，这样就会出现漏诊，会performing  fewer necessary ones than before，不符合题目要求）

open to discuss

vote for B

rockfish 解释得很好