求助：费费－21

21. Historian: We can learn about the medical history of individuals through chemical analysis of their hair. It is likely, for example, that Isaac Newton’s psychological problems were due to mercury poisoning; traces of mercury were found in his hair. Analysis is now being done on a lock of Beethoven’s hair. Although no convincing argument has shown that Beethoven ever had a venereal disease, some people hypothesize that venereal disease caused his deafness. Since mercury was commonly ingested in Beethoven’s time to treat venereal disease, if researchers find a trace of mercury in his hair, we can conclude that this hypothesis is correct.

Which one of the following is an assumption on which the historian’s argument depends?

A.        None of the mercury introduced into the body can be eliminated.

B.        Some people in Beethoven’s time did not ingest mercury.

C.        Mercury is an effective treatment for venereal disease.

D.       Mercury poisoning can cause deafness in people with venereal disease.

E.        Beethoven suffered from psychological problems of the same severity as Newton’s.

There should be 2 assumptions to support the hypothesis. The 1st assumption of the author is that only venereal disease will be treated by mercury in Beethoven’s time. The 2nd assumption is only some people in Beethoven's time will ingest mercury, if all people ingest mercury, the evidence is not useful. So, some people in Beethoven's time did not ingest mercury. The answer should be B.

A, E have nothing to do with the argument.

C is not necessary, 'Since mercury was commonly ingested in Beethoven’s time to treat venereal disease' is enough.

D is wrong:  according to the author, it is the venereal disease that will cause the deafness, not the mercury poison.

这道题看了Ｎ多遍也没看懂解释里的第二个假设的含义，怎么也想不通，求助ＮＮ，快考试了。多谢了

第二个假设取非，也就是说在 in Beethoven’s time 有些人会吃水银（也就是有病没病都吃）。那么，根据原因mercury was commonly ingested in Beethoven’s time to treat venereal disease, if researchers find a trace of mercury in his hair, 你还能得出结论 venereal disease caused his deafness吗？

显然不能。find a trace of mercury in his hair可能是因为他有事没事的吞吃水银的结果，并不能证明他有venereal disease 病，也就无法证明是venereal disease 病造成他耳聋了。