82.
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. 答案为C，我没有异议。
但是关于题目有一点点的小问题。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。这句话的意思是说，经济可行性的门槛就是指（因为燃油发电厂需要使用比太阳能发电厂更多的油量的）每桶油的价格吗？
也就是说将太阳能转换成电能所需的成本减小，但是原材料的成本仍然保持不变（即使本应该使得原材料的使用减少了）。
问解释原因是吗？
所以C的意思就是说技术革新使得燃油发电厂的效率也提高了，以至于用油量并未减少。
不知道理解的是不是有问题？
困惑中！
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