一道费费的新题

ring_cheng

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 correcgt 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 appendictis invariably have medical conditions that are much less serious than appendicitis.

B.the misdiagnoses produced by this test are always instances of attributing appendicites 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 appendictis has more than one of the symptoms generally associated with appendicitis.

E. the only patients who are misdiagnosed using this thest are patients who lack one more of the symptoms that are generally associated with appendicitis.

B is the key offered by feifei, but i am really confused about whether B or C is the right answer. Lawyer 你在么？

也欢迎大家一起来讨论

[此贴子已经被作者于2005-4-1 19:14:42编辑过]

tuzq

当然是B啦，文章说那种scan是producing two misdiagnoses for every 98 correcgt diagnoses，后面又说， without, however, performing any fewer necessary ones than before。那就是说misdiagnoses只会把没有的查成有，而不会把有的查成没有。

C根本没有谈误诊，肯定是错的。

ring_cheng

谢谢楼上的，对于B我了解了，不过对于C（all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis）的作用还不是太了解。如果说人有病，而test 能够确诊他的确患有此病（不是把有病的误诊为没病的），是不是也说明necessary 手术不会减少呢？困惑！请指教！！

结论：Clearly, using this test, doctors can （一）largely avoid unnecessary removals of the appendix without, however, （二）performing any fewer necessary ones than before

mindfree

C does not exclude the possibility that those who are not diagnosed with A actually have A. If that is the case, "performing any fewer necessary ones than before" might not be true.

ring_cheng

get ya, mindfree. Thanks a million!

I got it as following: C（all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis）only talks about the right diagnose which does not affect the necessary surgeries, but it doesn't mention anything related with misdiagnose which is the only factor in this passage to affect both the necessary and the unnecessary surgeries. And B excludes the possibility that those who are not diagnosed with A actually have A.

BTW, in your words: "If that is the case, "performing any fewer necessary ones than before" might not be true." is supposed to be "If that is the case, " without performing any fewer necessary ones than before" might not be true.", isn't it? :-)