大全-3-19<---ethyl修改标题（Test3-19（讨论过，还不懂））

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？

关于发帖格式，请参考：

http://forum.chasedream.com/dispbbs.asp?boardID=24&ID=74827&page=1

关于这道题，讨论的非常多。意思就一个：

文章A-->B,

加强的一种方法就是：not A-->not B

原文：适应了低盐，现在高盐-->血压高

A：适应了高盐，现在还是高盐-->血压低

而D说：低盐，现在还是低盐-->血压低

要注意，这里面的高盐是共同条件；因为题目突出的是现在突然变成高盐环境后，血压高了；那么说低盐环境里面的人血压低能起到什么作用呢。

我以为要A-->B，只能 非B->非A，但上文说 not A-->not B 也看可以加强。

到底是那种方式对？请诸位指教，谢谢！

同6楼问：

因果型结论：即原文给出两件事，然后得出结论说是一件事（因）导致另一件事（果）。SOPPORT该结论的方法包括：A。没有其他原因或可能导致该结果。B。结合因果：或有因有果或无果无因。C。因果不颠倒了。D显示因果关系的资料是准确。

not A-->not B 也看可以加强是啥意思呀？

genes that adapted to an environmental scarcity of salt.这段大家得理解哦。

文中说盐分高， 基因适应低的，-------}高血压比例高

d只能说明血压高跟基因有关，不能说明跟基因适应性有关。

大家讨论讨论。

B, C irrelevant. E weaken.

Between A and D.

Stem: high salt diet + gene of low salt  à high pressure.

D: high salt diet + gene of low salt à low pressure, D weaken.

A: high salt diet + gene of not-low salt à low pressure, A support.