求助FEIFEI-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.

分析说：

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.

我不明白为什么分析里说if all people ingest mercury, the evidence is not useful。。。

B感觉都跟题目没多大关系，有多少人ingest mercury什么关系？

B是不是排他法？

http://forum.chasedream.com/dispbbs.asp?boardID=24&ID=265174&page=2

对B取非 加入所有人都摄入汞， 既 得veneral disease 和 不得 veneral disease 的人都摄入汞，这样就无法判别Beethoven是否得veneral disease ,那么结论就不成立了。