大全-9-17

17.   There is a great deal of geographical variation in the frequency of many surgical procedures—up to tenfold variation per hundred thousand between 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.

为什么答案是B？ 原文没看懂

谢谢

原文意思：很多手术程序的变化，各地差别很大。对于10万个H，P，T病的手术，这种差别高达10倍。即比如A地只有1种手术程序，B地可能有10种手术程序。

B说着种差别和应该考虑的因素无关。将B取非，如果这种差别和应该考虑的因素有关，则结论说差别不必要就不成立。

哦，我明白了

非常感谢

Is it necessary to 'other than' in answer B?

Our purpose is that we need to make sure that other than unnecessary surgeries no other factors that affect the variations in number of operations by geography.

By using 'other than' the answer B explains that variation is only because of the surgical procedures alone. This only prove the other way around.

zilong,

you make me confused.