求助OG紫色53题

crystalvine212

53．There is a great deal of geographical variation in the frequency of many surgical procedures—up to tenfold variation per hundred thousand people among different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies．
To support a conclusion that much of the variation is due to unnecessary surgical procedures，it would be most important to establish which of the following?
(A)A local board of review at each hospital examines the records of every operation to determine whether the surgical procedure was necessary．
(B)The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered．
(C)There are several categories of surgical procedure(other than hysterectomies， prostatectomies，and tonsillectomies)that are often performed unnecessarily．
(D)For certain surgical procedures．it is difficult to determine after the operation whether the procedures were necessary or whether alternative treatment would have succeeded．
(E)With respect to how often they are performed unnecessarily, hysterectomies，prostatectomies，and tonsillectomies are representative of surgical procedures in general．

答案是B

hughlv

倒推一下逻辑：

题干：不同地区的相同基础人群中手术比例非常不同
结论：有很多手术是没必要的
推导：假如一个地区的人得某病的概率要远大于另一个地区，那么这个地区做这类手术的比例自然应该高一些。因此为了能得出结论，必须证明这个假设不成立，或者假设与结论之前不存在直接的联系。B就是这个意思了。

CDE比较容易排除，我倒是多看了会A，但是确实它不是很关键的原因。