23.(29107-!-item-!-188;#058&003854)
From 1978 to 1988, beverage containers accounted for a steadily decreasing percentage of the total weight of household garbage in the United States.The increasingly widespread practice of recycling aluminum and glass was responsible for most of this decline.However, although aluminum recycling was more widely practiced in this period than glass recycling, it was found that the weight of glass bottles in household garbage declined by a greater percentage than the weight of aluminum cans.
Which of the following, if true of the United States in the period 1978 to 1988, most helps to account for the finding?
(A) Glass bottles are significantly heavier than aluminum cans of comparable size.
(B) Recycled aluminum cans were almost all beverage containers, but a significant fraction of the recycled glass bottles had contained products other than beverages.
(C) Manufacturers replaced many glass bottles, but few aluminum cans, with plastic containers.
(D) The total weight of glass bottles purchased by households increased at a slightly faster rate than the total weight of aluminum cans.
(E) In many areas, glass bottles had to be sorted by color of the glass before being recycled, whereas aluminum cans required no sorting.
看过原来的讨论帖，还是不太懂，正确答案是C，但是对A有疑惑，我是这么理解A的：
因为玻璃的重量重，所以即使较少玻璃瓶的减少也会导致总垃圾重量的大幅减少；
而铝制瓶因为比较轻，所以即使铝制瓶回收的更多，可能并不导致总垃圾重量的大幅减少。
如果说原来垃圾总重量是100KG，
一个玻璃瓶3KG，15个玻璃瓶，45KG，
一个铝制瓶1KG，30个铝制瓶，30KG。
那么接下来减少了10个玻璃瓶，30KG，和20个铝制瓶，20KG，
现在的垃圾总重量就是50KG，有5个玻璃瓶，15KG，和10个铝制瓶，10KG；
原来玻璃瓶的百分比是45/100=45%，铝制瓶的百分比是30/100=30%；
现在玻璃瓶的百分比是15/50=30%，铝制瓶的百分比是10/50=20%；
所以玻璃瓶下降的百分比（45%-30%=15%）>铝制瓶下降的百分比（30%-20%=10%）
所以A是对的阿~！！ | 
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发表于 2011-11-11 09:05:30
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