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标题: 一道题，麻烦解答 [打印本页]

作者: helenwolf 时间: 2009-4-25 01:29
标题: 一道题，麻烦解答

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.

答案C的道理我知道，我想问的既然山区的矿贵，那么为什么这些人不在法规出来之前就去便宜的地方采，为啥非要等到法规出来了然后再去便宜的地方，这个有点不符合正常逻辑啊，还是我想错了，麻烦解答，另外问一下考过的，作文和Prep 大概要多久能看完，我现在还有1个月考试。谢谢了！！

作者: helenwolf 时间: 2009-4-29 16:41
谁来看看我的问题啊

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