NOmoreTears 发表于 2009-2-19 14:59
Taxpayer的反对是说ECC的cost高 没错 但是D选项在讨论ECC在concrete bridge 之外的用途 跟原题讨论出现偏差 ...
GWD21-Q3:
Highway Official: When resurfacing our concrete bridges, we should use electrically conductive concrete (ECC) rather than standard concrete. In the winter, ECC can be heated by passing an electric current through it, thereby preventing ice buildup. The cost of the electricity needed is substantially lower than the cost of the deicing salt we currently use.
Taxpayer: But construction costs for ECC are much higher than for standard concrete, so your proposal is probably not justifiable on economic grounds.
Which of the following, if true, could best be used to support the highway official’s proposal in the face of the taxpayer’s objection?
A. The use of de-icing salt causes corrosion of the reinforcing steel in concrete bridge decks and damage to the concrete itself, thereby considerably shortening the useful life of concrete bridges.
B. Severe icing conditions can cause power outages and slow down the work of emergency crews trying to get power restored.
C. In weather conditions conducive to icing, ice generally forms on the concrete surfaces of bridges well before it forms on parts of the roadway that go over solid ground.
D. Aside from its potential use for de-icing bridges, ECC might also be an effective means of keeping other concrete structures such as parking garages and airport runways ice free. (A)
E. If ECC were to be used for a bridge surface, the electric current would be turned on only at times at which ice was likely to form.
为什么D不对？Taxpayer的反对是说ECC的cost高，感觉A是无关阿
Taxpayer的反对是说ECC的cost高 没错 但是D选项在讨论ECC在concrete bridge 之外的用途 跟原题讨论出现偏差
A说明了如果用现在的方法解冻 会出现。。。问题 凸显出了ECC的必要性 美国人想问题不需要充分性 “有这种可能性”就行了
好比我说：马上要搬新家了 还是决定买用筷子 吃饭比用刀叉吃饭舒服 方便
你说：但是如果现在将家里的刀叉都换掉 成本太高
我说：用刀叉会会增加我们戳伤自己的可能性（同A）
我说：筷子除了吃饭以外还能用来掏耳朵（同D）
你觉得那个理由更能支持我用筷子的决定?
祝好运！
D) out of scope: the effectiveness of ECC in somewhere else can't be applied to the bridge case.So,D proves nothing.
A) gives another fact to support the Highway official's statement that ECC is better than salt by citing one disadvantage of de-icing salt (in the dialague, H. Official has cited one disadvantage of de-icing in terms of cost expenditure)
Hope it's helpful
我想问E为什么不对？只有当雪可能形成的时候才有电流通过不医院可以省cost吗？谢谢
解题的关键是 ECC are much higher than for standard concrete 的削弱
A就是bridge这个削弱
E之说了ECC自己省钱 没说比Concrete造价便宜或者好处啊 您再省电可是造价还是比人家高啊 等于造价高+稍微省电〉concrete
A，选项之所以对，主要是因为这句话：shortening the useful life of concrete bridges。如果桥的寿命缩短了，那么它的cost也会增加。
就好象你用100块买一双鞋可以穿三年，与你用50块买双鞋，只能穿1年是一个道理。
一开始看起来50元比较划算，但实际上用一百块买一双可以穿3年的鞋更实惠
对~~~这似乎又跟上次一道有关机器与使用次数的关系题有点像了。分摊到使用各年上，新的建设并不比旧的贵
NOmoreTears 发表于 2009-2-19 14:59
Taxpayer的反对是说ECC的cost高 没错 但是D选项在讨论ECC在concrete bridge 之外的用途 跟原题讨论出现偏差 ...
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