1.        GWD-17-Q11

Because visual inspection cannot reliably distinguish certain skin discolorations from skin cancers, dermatologists at clinics have needed to perform tests of skin tissue taken from patients.  At Westville
            Hospital, dermatological diagnostic costs were reduced by the purchase of a new imaging machine that diagnoses skin cancer in such cases as reliably as the tissue tests do.  Consequently, even though the machine is expensive, a dermatological clinic in Westville is considering buying one to reduce diagnostic costs.

Which of the following would it be most useful for the clinic to establish in order to make its decision?

1. Whether the visits of patients who require diagnosis of skin discolorations tend to be shorter in duration at the clinic than at the hospital

2. Whether the principles on which the machine operates have been known to science for a long time

3. Whether the machine at the clinic would get significantly less heavy use than the machine at the hospital does

4. Whether in certain cases of skin discoloration, visual inspection is sufficient to make a diagnosis of skin cancer

5. Whether hospitals in other parts of the country have purchased such imaging machines

C     

答案是C。想了半天，答案的意思是说，使用的频率来决定是否购入这样一台机器。

但是感觉答案和题干的条件有点远。题干是说这台机器能通过图片成像，也就是visual inspection来判断皮肤色斑是否为皮肤癌。那么，显得和答案GAP有点大。

请NN指教。

我选C.

也觉得文章比题目难一些 可能我抽象名词不认识有关.

这道题关键在cost和expense,因为At Westville
        Hospital, dermatological diagnostic costs were reduced even though the machine is expensive, 所以a dermatological clinic in Westville is considering buying one to reduce diagnostic costs，这里明显缺少一个条件：使用率是否能保证，而C恰好能弥补这个GAP，对吧

这题我开始在A和C之间很为难，显然B/D/E这三项容易排除，后来明白了：A的要素是患者候诊时间，C的要素是使用频率。一台机器成像诊断和皮试诊断效果相同，却能给医院带来更多收益（文中是节约成本），只能是使用率高的结果。

两个不同的方案,如果一个方案的初始投资大,而且这个方案还是一个在成本上有优势的方案,那么必定是这个方案后期的运维成本低(或收益高),而且还得是使用率非常高,这样的话,才能抵消初始投资大带来的弊端.