以下是引用JerryGuan在2004-12-11 1:22:00的发言：Q37:
Because mining and refining nickel is costly, researchers have developed an alternative method for extracting nickel using Streptanthus
polygaloides, a plant that absorbs and
stores nickel form the soil as it grows. The researchers incinerated a crop of Streptanthus they grew in nickel-rich soil. By chemically extracting nickel from 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 on 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. 这题太迷人了。。。不是因为美丽，而是它总让犯错。 给出的答案是B，我做的是D。我仔细看答案，后来渐渐明白了。 发出来讨论讨论。看看大家的见解。
管兄，我也选了D，关键是没有理解unusually到底表达个什么意思； 正如楼上有人说：“D是说试验采用的方法太好了，如果实际没那么好，就会提高成本，是削弱项。” 看问题的时候也要注意，呵呵。
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发表于 2005-7-2 21:34:00
