这道题肯定不是C

yya

新prep上的一题，答案是C ,可是本人认为A跟好，请教各位大牛

Technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade.However, the threshold of economic viability for solar power (that is, the price per barrel to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) is unchanged at thirty-five dollars.

Which of the following, if true, does most to help explain why the increased cost-efficiency of solar power has not decreased its threshold of economic viability?

A. The cost of oil has fallen dramatically.

B. The reduction in the cost of solar-power equipment has occurred despite increased raw material costs for that equipment.

C. Technological changes have increased the efficiency of oil-fired power plants.

D. Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants.

E. When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.

alinacandoit

看了一圈大佬的解读，现在我应该是完全理解了，我一开始把threshold理解成相对差值，出现了理解偏差。
“the threshold”：国家或者地区为了发展清洁能源，燃油发电的阈值需要提高，因为目前燃油发电的成本依然是偏低的。
简单来说，Cost for 1 electricity(solar)=oil price per barrel*the number of barrels for 1 electricity
“the threshold”=cost(solar)/the number of barrels（文章明确指出了per barrel）
cost减低，但是threshold不变，那只能是number of barrels降低，发一度电所需要的oil桶数下降其实就反应了efficiency的提升
如果按照A选项，cost降低，oil price降低很多，那么the number of barrels很有可能还会上升/不变（很小的可能会下降），才可以保持左右两边相等，那么the threshold可能降低/不变/上升，充满了不确定性，所以说明了oil price的变化无法说明the number of barrels的变化，所以也无法说明threshold。
还想补充一下，我看到有人说Cost不能够代表efficiency，所以不选A，但是果真如此吗。我不太认可，efficiency提升，cost就会下降啊，所以完全可以根据cost的变化判断efficiency的变化呀。

acebayarea

tu-yu 发表于 2020-9-6 11:57
完全不懂。。

你可以这样理解，两种方式solar和oil，当他们成本相等的时候：

fixed cost(solar equipment)+variable cost(solar)=fixed cost(oil plant)+ variable cost (oil price* oil consumption)

按照原文第一句话所说，太阳能发电现在的设备成本降低了，效率也提升了，所以等式左边下降了，那正常来说右边的成本因素也应该下降啊，但现在两者成本相等的临界平衡点还是35块钱，也就是说oil price还是35才能保持左右相等，那只能是oil consumption减少了，也就是说efficientcy提升了，这样左右才能相等

tu-yu

Vivian1091 发表于 2013-7-31 19:25
二楼讲的很清楚了。看曼哈顿论坛上tim举了例子说明这个道理，不懂的同学看下
This seems to be a popular ...

完全不懂。。

tu-yu

jiaoguitar 发表于 2012-3-15 11:54
我来稍微补充一下2楼的解释。题目说的是10年前与10年后每桶石油价格都需要增加到35刀(to which the oil ris ...

同意！               

你尝

(free solar+)conversion cost of solar=35+conversion cost of oil
要使等式成立只能在cc of s下降的时候让cc of oil跟着下降
而只有提升转换效率会降低cc

sillyzz

joeyqiushi 发表于 2019-6-12 23:52
其实这道题的难点在于理解题干。题干就是把简单的事情说复杂，把大家绕进去了。

题干直译：只有一桶石油的 ...

This explaination is fabulous, to me it's the best way to understand logic! Thanks!

jennay

同32楼，一开始看成了rise by （需要涨价35刀），所以选A合理。
看完各位大神解析，才发现原来自己是题目看错了= =！这道题说白了就是一道简单数学题。。

已知：

Solar Power Cost = solar price(which is 不要钱) + solar transfer cost

Oil Power Cost = oil price + oil transfer cost

（这里“threshold of economic viability”，说的也就是使得太阳能成本大于等于oil能的成本的阀值，即两年前oil price 为$35时Solar Power Cost =Oil Power Cost等式成立）

条件1，两年后，solar transfer cost 下降了

条件2，两年后，当Solar Power Cost = Oil Power Cost时，oil price $35 没变

求以下哪个选项依然能使得以上两个条件同时成立？

A: oil price 降低
C: oil transfer cost 降低

解：因为条件1:Solar Power Cost = solar transfer cost 降低，而Oil Power Cost = Solar Power Cost => Oil Power Cost = oil price+oil transfer cost 降低，而根据条件2: oil price 35不变 => oil transfer cost 降低 (选项 C)

（= =！I know）

jennay

1

洪小黑同學

看了这么多，还是LS解释的最清楚了。感谢