Technologicalimprovements and reduced equipment costs have made converting solar energydirectly into electricity far more cost-efficient in the last decade. However, the threshold of economic viabilityfor solar power (that is, the price per barrel to which oil would have to risein order for new solar power plants to be more economical than new oil-firedpower plants) is unchanged at thirty-five dollars. Which of thefollowing, if true, does most to help explain why the increased cost-efficiencyof solar power has not decreased its threshold of economic viability? A. The cost of oilhas fallen dramatically. B. The reduction inthe cost of solar-power equipment has occurred despite increased raw materialcosts for that equipment. C. Technologicalchanges have increased the efficiency of oil-fired power plants. D. Most electricityis generated by coal-fired or nuclear, rather than oil-fired, power plants. E. When the price of oilincreases, reserves of oil not previously worth exploiting become economicallyviable.
我买车，2万到是我的经济可行性临界值，超过2万我就不买了，低于2万我就买。汽车的价钱上升或降低到3万或者是1万都不影响我的 2万的经济可行性临界值，虽然我可以依据这个临界值做出买车的判断，3万了我就不买了，1万了我就买。我的经济可行性临界值是由我个人的经济能力的，也能是银行贷款利率，或者我的工资决定的，而不是由市场上车的价格决定的。
Ina similar sense, the reason the threshold of viability has not changed in this problem has nothingto do with the price of oil, but instead has to do with how cost-effective solar power is relativeto oil power. C does this by providing a scenario in which efficiencyincreases in solar power are balanced by efficiency increases in oil power.
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发表于 2011-9-20 20:57:26
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楼主
明白了~O(∩_∩)O谢谢
