求助一道prep CR。。。

秋晨小仔

82.(33511-!-item-!-188;#058&007598)



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.

为啥选Ｃ？
Converting solar energy into electricity is far more cost-efficient

Threshold of economic viability for solar power is unchanged

The price per barrel to which oil would have to rise in order for new solar power plants to be more economical is unchanged



是不是科技进步还有equipment cost已经让太阳能转换更cost-efficient了，但是供给让solar energy继续保持优势的油价依旧是每升35刀？
这个threshold在这儿是什么意思啊我这个题都看不懂。。。
括号里那句话怎么理解？对解题有用吗。。。看不懂啊55555

maimai7oo

感谢分享！               

秋晨小仔

解释经济门槛：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。 读这段，能发现油价是门槛，只有( ratio of efficiencies of oil power equipment / solar power equipment) 上升或者下降，这个门槛才会变化。


各种因素使太阳能发电的性价比更高，但是经济门槛没有随着性价比高降低，这是why咧？


因为 C. Technological changes have increased the efficiency of oil-fired power plants.就是说技术进步让 oil-fired power plants也变得更加高效了。所以即使用太阳能的性价比提高了，但是 oil-fired power plants的性价比也提高了。所以两个一中和，使用太阳能的经济门槛还是没有变化。

-- by 会员 单调唱 (2012/5/13 21:42:52)

多谢单调哥~

秋晨小仔

@单调唱 我是女鬼我自豪
@怪蜀黍 =。= 笑神马你。。.。。 这两天工作挺忙的啊大叔？

-- by 会员 上邪 (2012/5/14 9:13:06)

谢谢啦~~哈哈~~

上邪

@单调唱 我是女鬼我自豪
@怪蜀黍 =。= 笑神马你。。.。。 这两天工作挺忙的啊大叔？

yakev6

上邪妹的头像有点吓人啊。。阴深深的~

the key here is the definetion of threshold:

the threshold of economic is a benchmark of price
it is reached when new solar power plants is more economical than new oil-fired power plants

the background information tells us that the declining costs have made new solar power more cost-efficient
we expect the benchmark to rise because of the increased economical solar power
however it does not happen
we can make it into elements: A/B=A+/B+
THAT IS exactly what C means

i once choosed A but the argument is concerned not with cost of oil but with cost-efficient=economical of oil

-- by 会员 上邪 (2012/5/13 21:50:50)

-- by 会员 单调唱 (2012/5/14 0:04:17)

单调唱

上邪妹的头像有点吓人啊。。阴深深的~

the key here is the definetion of threshold:

the threshold of economic is a benchmark of price
it is reached when new solar power plants is more economical than new oil-fired power plants

the background information tells us that the declining costs have made new solar power more cost-efficient
we expect the benchmark to rise because of the increased economical solar power
however it does not happen
we can make it into elements: A/B=A+/B+
THAT IS exactly what C means

i once choosed A but the argument is concerned not with cost of oil but with cost-efficient=economical of oil

-- by 会员 上邪 (2012/5/13 21:50:50)

上邪

the key here is the definetion of threshold:

the threshold of economic is a benchmark of price
it is reached when new solar power plants is more economical than new oil-fired power plants

the background information tells us that the declining costs have made new solar power more cost-efficient
we expect the benchmark to rise because of the increased economical solar power
however it does not happen
we can make it into elements: A/B=A+/B+
THAT IS exactly what C means

i once choosed A but the argument is concerned not with cost of oil but with cost-efficient=economical of oil

单调唱

解释经济门槛：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。 读这段，能发现油价是门槛，只有( ratio of efficiencies of oil power equipment / solar power equipment) 上升或者下降，这个门槛才会变化。


各种因素使太阳能发电的性价比更高，但是经济门槛没有随着性价比高降低，这是why咧？


因为 C. Technological changes have increased the efficiency of oil-fired power plants.就是说技术进步让 oil-fired power plants也变得更加高效了。所以即使用太阳能的性价比提高了，但是 oil-fired power plants的性价比也提高了。所以两个一中和，使用太阳能的经济门槛还是没有变化。

秋晨小仔

小菜选c~我是排除做的~说实话我也没看懂~~帮顶一下~

-- by 会员 bob9603 (2012/5/13 19:16:36)

请问应该怎么排除呢。。我排除好弱。。。。