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Since 2004, when storm waters introduced Pacific carp to Hoffman Lake, the lake’spopulation of smallmouth bass has decreased by nearly one third. In the sametime period, the lake’s population of sand trout has decreased by approximately40%. Still, Hoffman Lake is home to more sand trout than to any other type offish.
Which of the following must be true on thebasis of the statements above?
A.If plans to remove Pacific carp from Lake Hoffman are successful, the populationof smallmouth bass and sand trout will increase. B.In 2004, there were more sand trout than any other type of fish in Lake Hoffman. C.Pacific carp are a natural predator of sand trout and smallmouth bass. D.At some point there were more sand trout in Lake Hoffman than smallmouth bass. E.If trends are to continue, Pacific carp will one day be the most numerous fish inHoffman Lake.
答案是D我选B，另外三个都很好排除。之所以选B是觉得有“still”这个词语，就表明以前trout也是数量最多的，而at some point则说明有时候trout的数量不如bass多（但是按我的理解因为存在“still”就说明trout是最多的）然后我就选了B……然后答案的解析是这样写的： D. If you follow the mathematical logic of the stimulus, you can see that the remaining 60% of sand trout is a greater number than the remaining 67% of smallmouth bass, or: .6T > .67B (where T stands for the original number of Trout and B stands for the original number of Bass) This means that T > B, proving that at some point (right around 2004) there were more sand trout than smallmouth bass. Beware the other answer choices, which are not necessarily true. For B, you don't know whether other types of fish were even more numerous but suffered a greater decrease.？？？没理解
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发表于 2017-8-21 17:07:19
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