标题: 请教OG12版 --7 [打印本页] 作者: alicejingli 时间: 2010-10-6 11:01 标题: 请教OG12版 --7 7. Traverton’s city council wants to minimize the city’s average yearly expenditures on its traffi c signal lights and so is considering replacing the incandescent bulbs currently in use with arrays of light-emitting diodes (LEDs) as the incandescent bulbs burn out. Compared to incandescent bulbs, LED arrays consume significantly less energy and cost no more to purchase. Moreover, the costs associated with the conversion of existing fixtures so as to accept LED arrays would be minimal. Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs? (A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs (B) Whether any cities have switched from incandescent lights in their traffi c signals to lighting elements other than LED arrays (C) Whether the company from which Traverton currently buys incandescent bulbs for traffi c signals also sells LED arrays (D) Whether Traverton’s city council plans to increase the number of traffi c signal lights in Traverton (E) Whether the crews that currently replace incandescent bulbs in Traverton’s traffi c signals know how to convert the existing fi xtures so as to accept LED arrays 我想问这道题为啥不能选E。 我的思路：首先是一道评价题。然后评价的是结论，老师说的肯定和原因特别相关。那E不就是说得和原文的原因吗？（原文原因：Moreover, the costs associated with the conversion of existing fixtures so as to accept LED arrays would be minimal）不就是说转换成本吗？作者: judydongxueni 时间: 2010-10-6 18:09
汗，他们不懂怎么换就找别人换呗作者: aomeisoft7 时间: 2010-10-6 21:29
(E) Whether the crews that currently replace incandescent bulbs in Traverton’s traffi c signals know how to convert the existing fi xtures so as to accept LED arrays 你没看明白这句话 E的意思是：是否工作人员知道怎么换
这题的结论是：要换LED 为了minimize the city’s average yearly expenditures E和这个结论一点关系都没有 A 选项谈到使用寿命，如果LED寿命短，要经常的换，成本就会很高了，所以这个是评价结论的关键作者: hjxsparrow 时间: 2010-10-7 00:55
花费= 电费+灯泡成本 而灯泡成本= 灯泡单价 x 更换频率， 更换频率 与 使用寿命成反比 A 考虑的就是更换频率 E 是一个明显的无关选项作者: alicejingli 时间: 2010-10-7 11:56
明白了，谢谢大家作者: 木寻云 时间: 2012-9-12 21:04
这一题我想请问，灯泡成本不是已经说LED arrays cost no more to purchase 这里，是指“灯泡成本= 灯泡单价 x 更换频率”中的成本(cost)；还是只是指灯泡单价(price)？ 原文中明明是说的cost吧~~~