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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
OA is C
OG对照版： Tiger beetles are such fast runners that they can capture virtually 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 a 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 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 stops and runs away without its usual intermittent stopping. B. In pursing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses. C. In pursing 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 beetle pauses, it has not gained on the insect it is pausing, the beetle generally ends its pursuit. E. The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.
OA is B
争议选项都集中在B和C（两题都是）
OG的明显好理解一些： B选项support了blind的那个解释undermine了那个体力不支的解释（因为如果他的prey是在绕着飞行的，他就需要更频繁的停下来来re-oriented),这就与beetles飞起来就看不见东西的选项吻合了。加强了这个，同时削弱了那个体力不支的选项（有些同学理解因为要跟着prey绕着飞所以体力更容易消耗，请不要这样钻牛角尖。。。） C选项的话第一个分句实际上削弱了视力不好的解释，第二个分句也削弱了体力不支的解释（如果是体力不支，上坡休息的应该比下坡频繁）， 所以不符合条件（support one while undermining the other) PREP的B选项可以由此排除 但是C选项。。。说beetles每飞一段固定的时间就要停顿一下，即使当他看到prey由静止变成了运动了，他也只是在停顿过后飞的更快。所以。。我总结了大家的 理解1：这是在support体力不支的选项而undermine看不见的那个选项。因为：1已经看到猎物飞走了还要每隔一段时间休息一下不是很蠢 么，只可能是飞不动了，2如果已经看不见了后来又要加速追赶不是更加看不见了么。。。 理解2：这是在support视力不好的解释而undermine体力不支的解释，因为后面说道加速，但是前面有说每隔一段固定时间休息一下，如果是 加速飞行的话体力不支的更厉害，应该缩短休息时间，而现在这样的做法（每隔一段固定时间休息一下，只是因为每隔一段时间就要 定位一下，看一下周围的情况，同时，在上次停顿后看清后可以飞的更快。
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发表于 2009-10-5 14:52:00
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