球大牛指教

wakesleep2011

In parts of South America, vitamin-A deficiency is a serious health problem, especially among children.  In one region, agriculturists hope to improve nutrition by encouraging farmers to plant a new variety of sweet potato called SPK004 that is rich in betacarotene, which the body converts into vitamin A.  The
plan has good chances of success, since sweet potato is a staple of the region’s diet and agriculture, and the varieties currently grown contain little beta-carotene.
Which of the following, if true, most strongly supports the prediction that the plan will succeed?
A. There are other vegetables currently grown in the region that contain more beta-carotene than the currently cultivated varieties of sweet potato do.
B. The flesh of SPK004 differs from that of the currently cultivated sweet potatoes in color and texture, so traditional foods would look somewhat different when prepared from SPK004.
C. For successful cultivation of SPK004, a soil significantly richer in nitrogen is needed than is needed for the varieties of sweet potato currently cultivated in the region.
D. There are no other varieties of sweet potato that are significantly richer in beta-carotene than SPK004 is.
E. The currently cultivated varieties of sweet potato contain no important nutrients that SPK004 lacks.

wakesleep2011

b为什么不对？

jameshzd

B与题目无关啊~答案是D吗？
你可以具体说说你对B的看法吗？

camelo777

题目说的是在南非，vitamin-A deficiency 是一个很严重的健康问题。在某一个地区农业学家鼓励农民去种一种新的sweet potato called SPK004 ，这个SPK004含有大量的betacarotene,，那么人体吸收以后就可以补充维生素A。结论是，这个计划是很有可能成功的，因为sweet potato是当地的主要农作物和食物，并且当地现在种的别的种类的sweet potato都没有包含beta-carotene，也就是说只有这个SPK004能提供维生素A，所以它是有市场的。

问的是哪个选项支持
A无关，问题讨论的是这个plan的可行性，不是有没有别的更好的选择
B说这个SPK004和当地本来种的sweet potato在颜色和质感上不太一样，这首先肯定不是支持，还有一定削弱的成分，因为当地可能已经吃习惯原来的sweet potato，你来一个不一样的，他们可能不太接受，所以B也不对
C说要成功种植SPK004， a soil significantly richer in nitrogen is needed than is needed for the varieties of sweet potato，也就是说需要土壤里有更多的氮气，这肯定也不是支持，这说明新的SPK004不如以前的sweet potato好种，要求比较高，C也不对
D同A 一样，问题讨论的这个plan能不能成功，就算SPK004是唯一能向人们提供维生素A的，这个plan还是有可能不成功，比如说B中提到的，人们可能不喜欢这种样子不一样的
最后来看E，E说SPK004中不缺乏其他sweet potato中所含有的重要nutrients，这样就反驳了可能阻碍SPK004种植plan的一个反对意见（人们可以说虽然SPK004能提供维生素A，但别的sweet potato也能提供别的特殊营养成分，这样的话这个plan就不会那么成功了）

E削弱了一个反对意见，因此是支持