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题库 / Prep2008E1-CR-107
Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation of mined-out land. Since then, reclamation technology has not improved. Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect.
Which of the following, if true, most helps to account for the drop in reclamation costs described?
Even after Balzania began requiring surface mine operators to pay reclamation costs, coal mines in Balzania continued to be less expensive to operate than coal mines in almost any other country.
In the twenty years since the regulations took effect, the use of coal as a fuel has declined from the level it was at in the previous twenty years.
Mine operators have generally ceased surface mining in the mountainous areas of Balzania because reclamation costs per ton of coal produced are particularly high for mines in such areas.
Even after Balzania began requiring surface mine operators to pay reclamation costs, surface mines continued to produce coal at a lower total cost than underground mines.
As compared to twenty years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.
情景：二十年前，Balzania开始向开垦土地的人征收复垦费用。自从开始征收复垦费用后，比较奇怪的是，虽然复垦的技术没有变化，但是每吨的煤的复垦费用反而下降了。
答案预估：
直接寻找解释原文现象（为何虽然复垦的技术没有变化，但是每吨的煤的复垦费用反而下降了）的选项即可。
选项分析：
A选项： 就算Balzania开始要求矿主支付复垦费用，Balzania的煤矿依然比其他地方的煤矿要便宜。煤矿的价格与复垦成本无关。
B选项：自从施行限制法令之后的20年以来，用“煤”作为燃料的情况要比这个法令施行前的20年下降了。与复垦成本无关。
C选项：Correct. 矿主停止开采了在Balzania山地中的一些矿藏因为在那些矿藏的复垦成本非常的高。显然，本选项提出了20年前刚开始施行法令和现在的一个显著的不同点。以前什么都开采，现在只开采便宜的。解释了为什么现在的复垦成本反而下降了。
D选项：就算Balzania开始要求矿主支付复垦费用，在表面的矿藏仍然比开采地下矿藏成本要低一些。本选项与复垦成本为何下降无关。
E选项：相对于20年以前，Balzania现在开采的矿藏中很大一部分都是地面矿。矿藏类型不能解释成本。
Balzania平均的复垦费用the average reclamation cost（关键词），说明复垦收费的费用是有一个标准的，有的高有的底，有一个平均值；但如今该费用的平均价格降低为刚颁布复垦收费条例时期复垦费用的50%，很有可能就是人们放弃了对复垦费用较高的区域的煤矿开采，而只在复垦费用较低的区域开采。故选C。E选项没有说出本质的原因：现在很大一部分是地面矿=》因为地面矿的复垦收费较低=》平均价格低。
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