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。
数字相关题目:重点关注的h是average cost per ton=复垦钱/煤产量 A 选项没有提及两个分子分母的变化,B 选项说的是使用的煤炭数量减少,没提及总的开采数量 C选项说明了分子总的复垦成本的降低,正确; D 开采成本与分子分母都没有关系 E 地面矿和 地下矿的比例与分子分母都没有太大的关系
从类比方向看:此题类比的P:两个案例是收费时与收费后后20年 也就是现在 相同点是开垦技术没有提高 C:那么开垦前后的复垦费用也应该一样,找两个案例的不同,或者是举出一个反例C A 选项讨论收费后,但是没有涉及两个案例的不同点(注意continue) B选项讨论的是 收费前后20年,不是题目中的案例,时间点要履清楚 C 选项正确,虽然没有直接提出时间点,但是默认有复垦费用,就是收费开始时。说明了一个不同点就是以前什么都开采,现在只开采便宜的。 D选项 同A E选项没有C选项更有说服力
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