总结了一下大家的理解，请求牛回答这道非常态难题

ivyfeng

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。

求lawyer，stellaleigh这样的牛牛们回答！！

ivyfeng

哼哧哼哧把它顶上去！

沉香屑

果然很值得研究的题目哎，个人倾向于PREP C理解2.

一起顶

tobytao

我是这样理解PREP C选项的

Beetle发现猎物由不动转为逃跑了，之所以要经过下一次Pause才加速去追（而不是马上加速），正是因为这次Pause在调整其视力（视力不行）。而能够加速去追，则本身证明了体力没有问题。

能这样理解的关键是要把后两句话先作为一个以Although开头的整句来看。

所以，这个选项是在support停下来是因为视力，而undermine是因为体力。符合题目要求。

[此贴子已经被作者于2009/10/8 17:11:13编辑过]

ivyfeng

顶

CompuComedy

Prep

(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.}

我觉得这里关键还是阅读，主句在前，让步在后，就是说，尽管反应能跟上，也能加速，但是体力还是问题，因此是support体力不足观点，消弱反应，对；

其他，Prep的(A,B)就是OG的(A,C)是双消弱，reshuffle了顺序，其余无关选项。。。

myoka

The beetles maintain a fixed time interval between pauses  Fixed time 证明它是由于体力的问题每飞一段时间就休息吧

although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause 从静止到开始逃跑 这速度我想如果beetles的视力跟不上的话肯定会在此时pause, but没有提到他们因此停下来 而是继续保持fixed time between pauses 在next pause的时候再加速

ironpual

我觉得应该是这样的：
尽管prey从静止开始逃跑了，tiger beetle在靠近的过程中还是要在追捕的过程中固定时间停下，即使下一段时间内可以加速。这样解释的话，可以undermine体力的问题，因为在固定的时间内是可以一直加速的。但是需要停下，观察prey的位置，所以加强了tiger beetle在追捕过程中blind的解释。

can1995

hypothesis 1: 间歇性休息室因为无法维持高速运动太久。
to undermine: 发现运动更久也没问题。
hypothesis 2: 是因为高速运动时无法处理快速变化的目标视觉图像，因此需要停下来再次确认目标位置。
to undermine: 1)在目标没有变化时也需要停下来，比如目标为静止状态；2)目标有快速的移动时，也没有停下来。
C)选项可以加强假设1，同时削弱假设2。因为如果假设2成立，那么当insect从静止开始移动会导致tiger beetles的moving interval被影响，比如缩短当前的interval停下来重新确认目标位置。这个也加强了假设1，因为证明了外界条件改变不会导致一次飞行时间变长。

E)至少无法加强或者削弱假设1，也无法说一定能够加强假设2，因为这反应有可能是因为假设2，也有可能只是表明了tiger beetles在一次短跑中不能转弯而已。

我觉得C是反对hypo1，支持hypo2。反对hypo1是因为常理是追得快则累则追击时间短，如果不管追得快还是慢，追的时间是一样的那说明pause和rest无关。而the beetle increases its speed after its next pause说明这个beetles是在停下后才加速的，说明它需要停下看清prey提速了才判断是要加速，支持hypo2。

B是反对两者。首先反对hypo2很清楚因为beetles对变化反应快。然后反对hypo1是因为常理是上坡容易累要多休息而下坡反之，但是这个beetles上下坡pause频率一样，说明pause和rest无关。
E能支持hypo2，但不能weaken hypo1。
这道题需要太多常识，题目出的很不好，但考着了也没招。

bloodmary1028

myoka 发表于 2009-10-11 19:57
The beetles maintain a fixed time interval between pauses  Fixed time 证明它是由于体力的问题每 ...

同意！