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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. 答案是B 这到题用排除法 A，B，D，E可以排除，但是B 也不怎么make sense. 因为我怎么感觉B只是在削弱argument 1，对agmt 2没什么影响呢？ B：在increase speed的情况下，仍然keep constant interval of pauses,说明体力不是问题，但只能削弱1 啊，不能加强1啊？ 有一道GWD的姊妹题目是这样的： Tiger beetles are such fast runners that they can capture virtualy any nonflying insect. However, when running toward an insect, a tiger beetle will intermittently stop and then, a moment later, resume its attack. Perhaps the beetles cannot maintain their pace and must pause for moment's rest; but an alternative hypothesis is that while running, tiger beetles are unable to adequately 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 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 immidiately stops and runs away without its usual intermittent stopping.
B. In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.
C. In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline.
D. If, when a beele pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
E. The faster a beetle pursues and insect fleeing directly away from it, the more frequently the beetle stops.
The answer is B
OG says: What point would strengthen one of the two hypotheses and weaken the other? Consider the information provided in each answer choice, remembering that information that supports one hypothesis must necessarily detract from the other. Any information that is not about pursuit or theat affects the two hypotheses equally may be dismissed from consideration. If the frequency of stopping increases when the beetle follows a swerving insect and must constantly change its course, then the second hypothesis is strengthened; the beetle's pauses increase as the variety of visual information that it needs to deal with increases.
B Correct. This statement provides information that stengthens the 2nd hypothesis: the swerving pursuit and the resulting continual course adjustments appear to be forcing the beetle to stop with increasing frequency to sort out the erratic visual information.
红字说得很清楚，加强某个结论可以必然地削弱另一个，但是不等于削弱一个结论等于必然地加强另一个结论啊？
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发表于 2007-7-18 13:15:00
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