TN24 11-37

crystal007

T-3-Q37.

Because mining and refining nickels is costly, researchers have developed an alternative method for extracting nickels using Streptanthus polygaloides, a plant that absorbs and stores nickel from the soil as it grows. The researchers incinerated a crop of Streptanthus they grow in nickel-rich soil. By chemically extracting nickel form the ash, they produced 100 pounds of nickel per acre of land at a total cost per pound slightly above that of current mining.

Which of the following, if true, most strongly supports the conclusion that the use of Streptanthus to extract nickel will be commercially adopted?

A.      The season in which the researchers grew Streptanthus was an unusually favorable one, with the right amount of precipitation to maximize the growth rate of Streptanthus.

B.       Because lowering the concentration of nickel in the soil can make land much better for agriculture in general, a plot in which Streptanthus has been grown and harvested can be sold for substantially more than it cost

C.      More air pollution is generated for each pound of nickel produced by extracting it from Streptanthus than is generated using conventional mining and refining

D.      The land on which the researchers planted Streptanthus was unusually free of the various weeds that can compete with Streptanthus for water, nutrients, and sunlight.

E.       It is extremely rare for soil to contain higher concentrations of nickel than the concentrations present in the researchers’ experimental plot.

我是這麼理解的

題目說用種植S的方法比原來採礦再精練的方法產量其實還比較少
                題目問
                怎麼樣可以支持種S讓種S的這個方法是commercially adopted的
                可以想見既然S方法產量比較少為什麼要支持呢?一定有其他的利益

選項B就是說
                用s的方法之後
                土地就會變的更肥沃可以賣更多錢
                就可以支持了

这是我在别的地方找到的 。觉得不对啊 首先并不是说用S产量少，而是费用略高。其次看B 意思：can be sold for substantially more than it cost是因为

种了S后可以lowering the concentration of nickel in the soil 从而可以make land much better for agriculture in general，这些traits用mining也可以达到啊，那不是也可以be sold for substantially more than it cost吗？ 

请指教！！！

esea

首先C,D,E 可排除掉，较明显。

A是说：研究者使S成长的季节不太适宜，如果有正确的降水量可以使让S的成长最大化。

这和a plant that absorbs and stores nickel from the soil as it grows 相联系的话，说明正确的降水量可以提高NICKEL每英亩的产量。

但请大家注意这句话at a total cost per pound slightly above that of current mining，说明计算成本的单位是生产每镑的NICKEL花了多少钱，

不是每英亩可以得到多少NICKEL。文中没提及单位面积的S产量越高，NICKEL生产成本越低，因为得到NICKEL要用化学的方法从S中得到，这部分的成本没提及，所以不可想当然。非正确项。

对于B,楼主的理解是用MINING方法减少了土壤中的NICKEL，那不是土壤也肥沃了，那也可卖出好价钱了，那可 commercially adopted 了。

这是不太了解MINING AND REFINING所致（请原谅我的直白），通常MINING AND REFINING是将矿石（含NICKEL的SOIL）通过物理或化学作用分成NICKEL和矿渣（几乎不含NICKEL的SOIL),这种SOIL是否肥沃和不肥沃不知道。其实这时确切的说不应该是SOIL，是矿渣。如果这有错误请学金属和冶金学的同学指正。

但GMAC说考试内容和专业背景无关，那不是有问题了？

这道题问的是要support conclusion 又要用S的方法得到在商业化上被采纳。

种植S生产NICKEL的成本比用采矿提炼的方法SLIGHTLY高，而把种完S的土地（PLOT）卖出去可SUBSTANTIALLY MORE THAN IT COST,

这样一出一进总体来看，就是盈利的，这样就可在商业化上被采纳。

这样就是B了

crystal007

谢谢详细细心的解答，我理解B选项有问题，觉得没有强调说是用S才能卖出substantially higher prices,是在强调S可以lower the concentration,所以自然推及MINING也可以卖出substantially higher prices.现在看来是错了。谢谢！！！！