請教逻辑大全Test 3: Q19-20

eddychasedream

以下2提還請各位幫忙協助，謝謝

19. Black Americans are, on the whole, about twice as likely as White Americans to develop high blood pressure. This likelihood also holds for westernized Black Africans when compared to White Africans.
Researchers have hypothesized that this predisposition in westernized Blacks may reflect an interaction between western high-salt diets and genes that adapted to an environmental scarcity of salt.
Which of the following statements about present-day, westernized Black Africans, if true, would most tend to confirm the researchers’ hypothesis?
(A) The blood pressures of those descended from peoples situated throughout their history in Senegal and Gambia, where salt was always available, are low.
(B) The unusually high salt consumption in certain areas of Africa represents a serious health problem.
(C) Because of their blood pressure levels, most White Africans have markedly decreased their salt consumption.
(D) Blood pressures are low among the Yoruba, who, throughout their history, have been situated far inland from sources of sea salt and far south of Saharan salt mines.
(E) No significant differences in salt metabolism have been found between those people who have had salt available throughout their history and those who have not.
答案是A，我也猜了A但是不知道為何Africans在非洲鹽很充裕，但是為何blood pressure還是低?


20.The following proposal to amend the bylaws of an organization was circulated to its members for comment.
When more than one nominee is to be named for an office, prospective nominees must consent to nomination and before giving such consent must be told who the other nominees will be.
Which of the following comments concerning the logic of the proposal is accurate if it cannot be known who the actual nominees are until prospective nominees have given their consent to be nominated?

(A) The proposal would make it possible for each of several nominees for an office to be aware of who all of the other nominees are.
(B) The proposal would widen the choice available to those choosing among the nominees.
(C) If there are several prospective nominees, the proposal would deny the last nominee equal treatment with the first.
(D) The proposal would enable a prospective nominee to withdraw from competition with a specific person without making that withdrawal known.
(E) If there is more than one prospective nominee, the proposal would make it impossible for anyone to become a nominee.
答案是E，我選了D但是不知道為何D說的可以退出選舉不能當答案?

以上還請幫忙，謝謝

lmf0801

第一题 取非 应该可以  题上说 西化黑人高血压是由于西方高盐饮食和缺盐基因相互作用的结果  
A选项 说不缺盐基因的非洲人 血压低  取非 刚好和题目的结论相矛盾

第二题 还不懂等高人求教

sdcar2010

For number 2 question, the reason is simple.  Who would give the FIRST consent to the normination?  Nobody! The reason is that before the first norminee gives his consent to be norminated, he must be told who the other norminees will be.  But there is no way anyone can say for sure who would be giving their consent to the normination before hand. In addition, no one has committed yet since this candidate is supposed to be the first to give consent!

The same logic goes for other candidates as well.  No one can give their consent since no one can predict who would be among the final candidates.  Even God does not know that!

lmf0801

That is a so interesting explain    THS very much

eddychasedream

Thank you all very much

ashley0707

（A）题目说的是黑人有高血压是因为缺盐然后A里面说那些不缺盐的地方血压都很低，原命题的逆否命题成立的。错选D。题目缺盐-高血压，A：不缺盐-低血压，D：缺盐-低血压，可见D反了