费费两道-请指教

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.

答案是B为什么呢? Total 不明白

36. Sometimes when their trainer gives the hand signal for “Do something creative together” two dolphins circle a pool in tandem and then leap through the air simultaneously. On the other occasions, the same signal elicits synchronized backward swims or tail-waving. These behaviors are not simply learned responses to a given stimulus. Rather, dolphins are capable of higher cognitive functions that may include the use of language and forethought.

Which one of the following, if true, most strengthens the argument?

(A) Mammals have some resemblance to one another with respect to bodily function and brain structure.

(B) The dolphins often exhibit complex new responses to the hand signal.

(C) The dolphins are given food incentives as part of their training.

(D) Dolphins do not interact with humans the way they interact with one another.

(E) Some of the behaviors mentioned are exhibited by dolphins in their natural habitat

答案是B, 同上， 不明白，请指教

我的看法：

21题：

原文是说：在贝多芬时代， ingest mercury是常用的治疗venereal disease的方法，如果researcher可以在贝多芬头发里找到mercury,则可以得出结论：贝多芬ever had a venereal disease。

这个推论成立的前提必须是： mercury是只有在治疗venereal disease 的时候才会被ingest，其他情况人们不会ingest(不然的话，大家有事没事都可以去ingest mercury,那是不可能用这个方法来推出贝多芬有venereal disease的）。既然如此，那肯定会存在一些人不ingest mercury，所以它就是答案。