请教OG-202

202.
Gortland has long been narrowly self-sufficient in both grain and meat. However, as per capita
income in Gortland has risen toward the world average, per capita consumption of meat has
also risen toward the world average, and it takes several pounds of grain to produce one
pound of meat. Therefore, since per capita income continues to rise, whereas domestic grain
production will not increase, Gortland will soon have to import either grain or meat or both.
Which of the following is an assumption on which the argument depends?
(A) The total acreage devoted to grain production in Gortland will not decrease substantially.
(B) The population of Gortland has remained relatively constant during the country’s years of
growing prosperity.
(C) The per capita consumption of meat in Gortland is roughly the same across all income
levels.
(D) In Gortland, neither meat nor grain is subject to government price controls.
(E) People in Gortland who increase their consumption of meat will not radically decrease
their consumption of grain.

这道题OG答案选E。可是我觉得B也是对的，因为人均肉的消耗量增加了，如果总人口减少的话，肉的总消耗量是不变的，所以就不会产生以上的结果。所以这个结论也要建立在人口恒定的基础上。大家说呢？

这题我也问过，现在弄懂了。b不能是assumption,因为人口有可能增，也有可能减，增的时候你可以推得出 结论，但减的时候你是推不出结论，assumption 必须是必要条件，所以b错

Gortland has long been narrowly self-sufficient in both grain and meat. However, as per capita
income in Gortland has risen toward the world average, per capita consumption of meat has
also risen toward the world average, and it takes several pounds of grain to produce one
pound of meat. Therefore, since per capita income continues to rise, whereas domestic grain
production will not increase, Gortland will soon have to import either grain or meat or both.

结论是，由于grain跟不上income的增长速度， 所以要进口。其实就是说，grain的消费是增长的， 但是如果象E所言，就如果消费减少，就不用进口了。

对于B，1）人口的多少与comsumption 的关系， 原文没有定义 2）问题的关键是抓住income increase.

mikecat说得对，“人均肉的消耗量增加了，如果总人口减少的话，肉的总消耗量是不变的，所以就不会产生以上的结果”

但是，og对为什么不选B的解释是：人口增加的情况不会影响结论。

显然，og讲的“remain constant” 的默认值是not increase（人口减少的情况根本不在考虑之列）

想想也是，一般一个自己自足的穷国经济起飞之后都是人口激增，还没听说过这个时候负增长的。

即便不把“remain constant” 的默认成not increase，按取非削弱的方法，B选项的取非是inrease or decrease，如果是decrease就能削弱，如果是inrease就不能削弱；这样和E比较起来当然是E更好。

问一下E:

题中有个条件: 几 磅gain 生产 1 磅meat.  这里可能有个推理: 人们转向消费meat而省下来的gain不够用来生产足够的meat.(E取反), 那么还是有可能要进口.

不懂为什么ETS加上磅数转换限制

3ks