标题: 一道GWD。。困惑中。。。看了解答仍不明白~ [打印本页] 作者: frieda030 时间: 2010-4-19 20:24 标题: 一道GWD。。困惑中。。。看了解答仍不明白~ 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. technology has not improved，但是average reclamation cost for a surface coal下降了，猜想肯定是他因导致 Which of the following, if true, most helps to account for the drop in reclamation costs described?
A. 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. B. 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. C. ！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. D. 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. E. As compared to twenty years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.
啥意思类？？作者: prayer 时间: 2010-4-19 20:35
operators of surface mines to pay for the reclamation of mined-out land这部分是regulation里花钱的； gmat里花的钱一般都会包括几部分：人工成本、材料成本、设备折旧等等，这里花的钱是reclamation的成本 ，但是会根据地理位置不同变化的。刚有regulation的时候可能是在reclamation成本高的地方，现在是在reclamation成本低的地方，这样就抵消了technology的那部分