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Test3
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.（A）
(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.
A
Why not D? 看过前人的讨论，没明白。
文章说high-salt diet and genetically lacking salt cause high blood pressure.两个条件推出一个结论， 这种问题怎么加强？
A． 结论是low blood pressure .salt was always available，应该是high-salt diet,但是给S和G两个地方的意思是说当地的人是Black people因此genetically lacking salt; 还是说salt was available in S and G, 因此genetically abundant of salt, 如果是前者，那么A就反对结论了。如果是后者，否定一个条件，得到否定结论，也可以作为加强吗？
D．结论是low blood pressure，条件是genetically lacking salt and low-salt diet, 也是否定一个条件，得到否定结论，为什么不对？
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发表于 2005-8-27 19:44:00
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