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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. 文中一开始说铝和玻璃的广泛运用降低了重量。不明白的是后半句，不明白为什么用although，没发现转折，而且又说了铝和玻璃的降低，没头没脑的：（
24. (29155-!-item-!-188;#058&003857) Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack. Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop. Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other? (A) When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and runs away without its usual intermittent stopping. (B) In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline. (C) The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause. (D) If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. (E) When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier. 为什么是C？觉得没有起到suppote一个 weaken另一个的目的啊？
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发表于 2007-5-18 00:48:00
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