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西风瘦马

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.

NN看看

woodsender

答案是C 但不懂 

OK_Computer

两种观点，因果关系相当明显：

A认为TB体能不行，所以经常停下来；

B认为TB眼睛不行，所以经常停下来。

正确答案为B，

前半句表明TB的眼睛没问题，削弱了B的观点（有因无果）

后半句表明TB确实有很大可能是由于体力不支而停下休息，支持A观点（有因有果）

Choice A，同时削弱A观点和B观点；

Choice C，同时加强A观点和B观点；

Choice D，搞笑选项；

Choice E，与原文因果关系无关

[此贴子已经被作者于2008-5-30 21:45:18编辑过]