此题意思是说,各地手术次数的差异很大-There is a great deal of geographical variation in the frequency of many surgical procedures,H、P、D是作者举的例子-up to tenfold variation per hundred thousand between different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies.
要得出的结论是:这些差异是由非必须的手术造成的(也就是说,手术可做可不做,有地方做了,有地方没有做,所以才会有差异)much of the variation is due to unnecessary surgical procedures
这之间有个GAP,B正好填补了这个GAP,即这种差异不是由导致手术的必要原因(非要做手术不可)造成的。The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered.
如果在B项中加NOT,也就是反过来想,如果手术与病因有关,而这种病因是需要手术来解决的——factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered,那各地都会手术,就不会有这个差异存在了。
A选项正好削弱了结论,如果每个地方在做手术之前都仔细的掂量过,那这个差异就很有可能由necessary surgical procedure导致的了。
[此贴子已经被作者于2005-3-8 20:09:04编辑过] |