xiongbaobao

T-4-Q2注意数学题是词汇。比如这里就是平均的概念
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. Use和开采之间还是需要补充说明不能自己推断
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.
选C,因为矿主差不多都停止了开采,所以 Balzania 收的钱的总数就少了,导致平均每吨的成本也就低了.