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?
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.
求助啊，一点都没有头绪。。。是不是选d呢
我觉得选B,它要求找一个能支持the drop in reclamation costs的。
可以倒着推倒，既然它对surface mine的收费下降了，一定是这些surface mine的公司效益不好。那么就要看那些原因会导致他们收益下降的。
A,生产成本低，profit就高，那么就应该对这些公司收费高点。所以不行。
B，对mine的需求少了，那么profit也就少了，自然收费也相应降低点。
C,有些地区可能成本高点，但是不具代表性。
D，E,有点类似于A
没有答案诶。tn24套的答案好像和这个答案对不起来，谁有答案分享一下
谢谢
| 欢迎光临 ChaseDream (https://forum.chasedream.com/) | Powered by Discuz! X3.3 |