OG12 07

gracehanyin

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 signifi cantly less energy

and cost no more to purchase. Moreover, the costs associated with the conversion of existing fi xtures 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
l
ikely 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

不太看得明白OG上对D的解释，

OG是这样说的
D： Increasing the number of traffi c signal lights in Traverton would probably increase the city’s
yearly maintenance costs, but it would do so regardless of whether those lights use LEDs or
incandescent bulbs

我在想D错误是不是因为他加了附加的条件上去，而且即使是要increase the number of traffic signal lights 那么用LED也比用incandescent bulbs更节约？？

justabeginning

我觉得这就是个单纯的无关选项呀……

或者你也可以这么看，如果回答no,即使city council 没有增加traffic light也不能达到削弱结论即：LED不能降低成本。
所以这个选项是错误的。

PS:我也是刚开始复习的，可能对问题的认识也有偏差……仅供参考……

vakaka

政府的目的是minimize the city’s average yearly expenditures on

its traffi c signal lights
但是如果是 increase the number of traffi c signal lights in

Traverton，无论如何费用都是会增加的，无所谓是LEd还是原先的，所以和

题目说的要不要换成LED是无关的

ScentyGuy

题目不是说leds arrays consume less energy and no more to purchase，怎么还需考虑 service life ？

ShirleyWong

题目问的是如何才能使得每年的维修成本最低，如果增加了信号灯，那么就会增加维修费用，因为有些坏了才会去增加信号灯；那如果不增加交通信号灯呢，那么相安无事，可能根本就没有需要增加维修费用，因此，就不能决定（determine)用led 灯费用是不是最小。看回A选项，回答是，那么维修费用就小，没有问题；回答不是，那么就无法起到减少最低费用的作用，因此，可以决定这个plan是不是有效~~