请教逻辑OG-153

tangnaibin

这道题目简直是一个高难数学题。

我觉得ETS的陷阱在于，题目中给出的条件太多，混淆了大家的视线，也浪费了很多不必要的脑细胞。我的理解是这样的，请大家指正：

第一句话technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade.基本上是废话，换算成公式来理解：分子都是总成本，分母是产生的能量值，这样solar energy far more cost-efficient；但是于本题不相干。

括号里面的解释，我通过google勾过，还是不明白the threshold of economic viability 的具体数学表达公式。所以我就武断地理解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为：每桶油用于new solar power plants发电的价格成本的提升和同样一桶油用于new oil-fired power plants发电的价格成本的提升相差35刀。这样的理解只能是the efficiency of oil-fired power plants提高了。而a选项中的油的单价显然起不到作用了。

请各位NN指教

ya-ya

以下是引用tangnaibin在2005-1-28 0:09:00的发言：

每桶油用于new solar power plants发电的价格成本的提升和同样一桶油用于new oil-fired power plants发电的价格成本的提升相差35刀。

这句话tangnaibin能再解释一下吗,实在没看懂

jonasjin

there are two foctors that influence the  economic viability for solar power. one is the price of oil and the other one is the relative cost of solar power plants to oil-fired
power plants. i.e
太阳能cost－火力cost＝35

火力cost doesn't include the oil cost,

here 35 is not current real  price for oil . 35 is the number just indicates the difference between these two power plants.  since ten year ago the number is 35  and now the number is still remain unchanged, and the cost of solar powar is decreasing. therefore the cost of power plants is decreasing too.

if this is a real case people will finally compare 35 with current oil price. if the oil price higher then 35, the solar pawer is ecnomically available, otherwise not . the reason why they didn't take the real oil price take in to the consideration mby be that because oil price is always fluctuating, so it is more convenient to rule  out the price for calculating and finally compare the number with real oil price to confirm whether it is economically available.

[此贴子已经被作者于2005-2-11 19:59:44编辑过]

mildsevens

刚好看到这个题,仔细看了几遍题目,感觉对threshold的解释是一个混淆，原油价格只是一个公式计算的参考值，并非两者成本计算得关键因素，要分析两者的差异，比较的应该是成本（比如，每千瓦时要多$），而非直接与原油价格比较。

商榷。

tuzq

天哪，刚刚发现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的意思其实是：原油每桶要涨到多少钱，才能。。。；而不是原油每桶要涨多少钱，才能。。。

郁闷！！！！！我做题的时候就觉得不对，现在每桶油也就是个30－40美金，怎么要涨那名多。

ya-ya

天那!!这个该死的"to which", 怎么就没看到呢......

tuzq真是救世主啊,呵呵...

BiteGmat

同意一位楼上的

太阳能电厂成本＝火电厂成本＝油价＋火电厂的其它成本

太阳能电厂成本下降，油价不变，可得火电厂的其它成本下降。

kevincao

我觉得这题的关键：threshold临界点，是由solar energy efficiency and power eneney efficiency 共同决定的，和具体的油价多少无关。

snowjing

http://forum.chasedream.com/dispbbs.asp?boardid=24&id=37371&star=3#1168533

swlfx

以下是引用mildsevens在2005-2-12 0:14:00的发言：

刚好看到这个题,仔细看了几遍题目,感觉对threshold的解释是一个混淆，原油价格只是一个公式计算的参考值，并非两者成本计算得关键因素，要分析两者的差异，比较的应该是成本（比如，每千瓦时要多$），而非直接与原油价格比较。

商榷。

有道理。