[求助]天山4-2

michaelchenma

正确答案是C。虽然通过排除法，其他都比C错的更厉害，但是有什么逻辑原因能推出C来吗？

Q2:
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.
Answer:
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laihong

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.

期待蔚蓝

以下是引用laihong在2005-11-21 18:40:00的发言：
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.

why?

E为什么不对啊？

晴天小狗

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.

原文：要求surface mines的人交钱

E. As compared to twenty years ago, a greater percentage of the coal mined in

Balzania today comes from surface mines.

E：现在surfice mines的有很多。那么如果如E所说，sur mines多的话应该交钱多啊。无法解释交钱少的现象

E：现在surfice mines的有很多。那么如果如E所说，sur mines多的话应该交钱多啊。无法解释交钱少的现象

[此贴子已经被作者于2006-11-9 21:36:13编辑过]

amysarmy

E说coal的tons 更多了..那么cost per ton就减少了..正好解释了题目啊..为什么不对呢..

MRFROG

这道题就看怎么算average reclamation cost，理解不同，答案就不一样。

celery118

按照5楼的说法，费用不是按照产量计算而是按照是否开采这一事实征收的

假设这个成立的话，那么法规实施以后，既然同样是要开采，为了使利润最大，老板们应该会想法设法的改进技术，提高产量

但是题目中已经说明了在征收之后，技术并没有提高。因此我认为是按照产量多少来计算的。所以选C

jamesyeah

up!有没有新的解释阿？经典一些!

gustavechi

平均征地开矿价格下降可能是1）技术提高效率，或是 2）征地开矿时耗费的总代价降低。题中已经说明技术没有变，那只能是征地开矿总耗费降低。直接在答案中找，发现在山区征用要比平地要贵，那么如果减少或放弃征用山地，那征地开矿总费用自然就降下来了。这样以征用平地为主的开矿方式，自然使征地开矿的均价降了下来。

所以我认为答案是C。

gonghao

http://forum.chasedream.com/dispbbs.asp?boardID=24&ID=84506&page=1