求解prep两道题。。。。我的脑回路可能太奇葩

patty00

1. 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.
• 
  
• 答案是C
• 我的问题时怎么解释B的错误？B说需求量上升，可能供不应求所以导致价格下降怎么不对了？
  

2. The country of Baurisia has, until now, been self-sufficient in both grain and meat. However, with growing prosperity in Baurisia has come a steadily increasing per capita consumption of meat, and it takes several pounds of grain to produce one pound of meat. Therefore, since per capita income in Baurisia is almost certain to rise further but increases in domestic grain production are highly unlikely, Baurisia is soon likely to become an importer of grain.
　　Which of the following, if true, most seriously weakens the argument?
　　A. When people increase their consumption of meat, they also tend to increase their consumption of grain.
　　B. The per capita consumption of meat in Baurisia is roughly the same across all income levels.
　　C. Per capita consumption of meat has not increased substantially in recent years in those countries from which Baurisia is likely to import meat.
　　D. It is more economical for Baurisians to import meat than grain.
　　E. During Baurisia's years of growing prosperity, the country's population has remained relatively stable.


答案是D，不懂B，B肉的人均消费量不随收入水平的变化，就是说人均收入就算变了，也不会影响肉的人均消费量，那这不是削弱了题干的since per capita income in Baurisia is almost certain to rise further，Baurisia is soon likely to become an importer of grain？？？？？？？


谢谢解答！

GPSGWJ

（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. B没有提需求量的事情呀 只是coal的使用量减少 楼主有些先入为主了
再看题目
premise 1: technology has not improved
conclusion: cost per ton has declined
要选一个答案（premise 2）完成 premise 1+2向conclusion的推理
B: use of coal declined 与单位面积cost下降无关

GPSGWJ

B. The per capita consumption of meat in Baurisia is roughly the same across all income levels.
意思是说 任何收入阶层人群的人均消费肉制品量是几乎相等的
换句话说就是月入1000的和月入1000万的平均都吃一样多的肉
而题干说的是人均消费量增加 与不同收入人群无关 只管平均下来的量 因此属于无关选项

patty00

GPSGWJ 发表于 2017-9-22 20:56
（B）In the twenty years since the regulations took effect, the use of coal as a fuel has declined f ...

B是说 市场上对coal的使用量减少了，那不就说明市场上对coal的需求量也减少了？
我是认为我理解错的地方应该是，需求量减少只能说明coal的销售价格会下降，和成本cost无关。。对吧？

GPSGWJ

patty00 发表于 2017-10-15 20:24
B是说 市场上对coal的使用量减少了，那不就说明市场上对coal的需求量也减少了？
我是认为我理解错的地方 ...

对的

honorcga

看一下！