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 because 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.


这道题答案给了C，我不太明白C如何加强了奔跑中的“虎虫”看不见快速移动的东西？为什么although那句强调无论目标动与不动都一样？

题干要求下列实验的DISCOVERY会UNDERMINE一个结论同时削弱另一个。C中The beetles maintain a fixed time interval between pauses说明B动物确实需要RUN一段时间然后休息下因为它有固定的停隙时间。although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause.说明它不会因为PREY的快速移动而变得视觉“模糊”，因为它完全可以针对快速移动的物体做出更快速的反应。

不过是如何加强“虫子的停歇是由于体力不足”这个结论的呢。另外另一个结论是“跑的过程中虫子视觉模糊”，停止之后能做出更快速的反应是否不能削弱这个结论？

C strengthens the alternative hypothesis and weakens the idea that they have to pause because they cannot maintain their pace and have to pause to rest.

The reason C weakens the idea that they have to pause to rest is that presumably, they pause because their strengths have given out.  However, C says that they pause at fixed intervals, and if the prey begins to flee, the tiger beetle will increase its speed after the pause.  This suggests that it pauses not because it has to rest to recuperate.  As it pauses at fixed intervals, and yet can expend more energy by running faster, it means that when the beetle paused before the change in speed, it has not become exhausted.  Thus it must have paused for other reasons.

The reason that C strengthens the alternative hypothesis is that the speed of the beetle did not increase the moment the prey begins to flee, but has to wait until the next pause.  This suggests that it did not see that the prey has begun to flee until it paused, which supports the idea that the beetle cannot process the changing visual information because it is running so fast.

[ 本帖最后由 Asrgbf 于 2008-5-1 00:25 编辑 ]

解答得真棒！我明白了
佩服

晕  OG11 一样的题目 怎么选项就不一样呢。。。