求助！PREP1-24

dontwanna

24.

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.


正确选项为C。为什么选项E不对啊？还有帮忙解释一下正确选项C,谢谢谢谢了！

howie0420

这道题的关键是需要找到一个实验，满足在支持某假设的时候还能够同时削弱另一个假设。

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。

dontwanna

我再仔细想想吧！谢谢了！

jingjane

请问。。。这道题是不是B两个都加强了？

anilolive

(B) In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction,削弱2 and pause equally frequently whether the chase is up or down an incline.因为能以平均的频率来pause,我感觉是支持了1，跑跑累了歇歇跑跑累了歇歇。。。。。谁帮我解释一下B好吗？

cherryser

24.

Tiger beetles are such fast runners that they can capture virtually any nonflying insec ...
dontwanna 发表于 2013-4-22 07:14

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。

xuyuanwai

甲虫飞着飞着要停有两个可能的原因，一是因为累的跑不动（体力论），二是调整视力（视力论）

(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.
当猎物面对beetle飞来时，beetle马上跑走，没有边飞边停。与题目条件不符

(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.
追猎物时，beetle根据猎物的位置变化马上转变（否定视力论），并且无论猎物上坡还是下坡都以一样的频率休息（否定体力论，假若支持累要休息，上坡休息应该更频繁）。此选项2个原因都否定了

(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.
beetle休息之间的时间是固定的，尽管当一只静止不动的猎物准备逃跑时，beetle在下一次休息后会加快速度。每次飞的时间固定，但是会加速，否定了体力论（若支持体力论，速度快时飞的时间应该短）。支持了视力论，beetle体力没有问题，可还是要pause，其目的就是要定位，看准了方向再加速

(D) If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
如果当beetle休息时，它还没有赶上它追的猎物，beetle就会结束追赶。无关项

(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.
当追赶过程中beetle前面有阻碍物时，beetle有时会立马停止，但是他们不会围障碍物转。无关项

windyYe

甲虫飞着飞着要停有两个可能的原因，一是因为累的跑不动（体力论），二是调整视力（视力论）

(A) When a ...
xuyuanwai 发表于 2013-4-29 06:56

此处的体力论，视力论，很形象，很有意思。
不过对于c的解释，我的看法正好和你完全相反。
（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.
我对前半句话的翻译是，就算有一只即将要逃跑的虫子禁止不动的摆在beetles的面前，beetles也不懂得珍惜，不是奋起直追，而需要走一步，歇一步。
如果说有一只虫不停地变化方向在跑，beetles在追逐过程中不停的歇，这才说明beetles的视力有问题，必须停下来判断变化的方向。

后半句，每次beetles休息之后跑的更快，我觉得很充分说明了是因为体力的问题。
我们自己跑步时也有相同的情况啊，跑累了，歇一会，接着跑的时候，速度会加快啊。只是跑跑跑跑，就又歇菜了，又需要停顿一下。不是吗？
所以说，beetles是因为体力的原因，才会出现跑跑停停的状况，只不过每次跑，都是减速运动，一开始最快，接着慢下来，最后停下来休息。接着再反复这样一个过程。

这题我也每次做，每次都错。
我觉得C也不是很完美，这个选项说明了是beetles的体力有问题，但没有说明beetles的视力就没问题。

zhanghaolin

LS没搞清楚，首先bettles maintain a fixed time interval betwwen pauses，说明跑和停是固定的，并非bettles跑得慢了就晚点休息，跑得快了体力消耗大了就快点休息，那说明体力没问题啊。即使当一个静止不动的虫子突然逃跑的时候，bettles也没有立刻追上去，而是先停下来，再加快速度，正是说明它要调整方向。如果按照你说它要走一步歇一步的话，在他体力完全没什么消耗的情况下，还要停下来干嘛，直接加速就好了。

Lhitachii

(B) In pursuing a moving insect, the beetlesusually respond immediately to changes in the insect's direction, and pauseequally frequently whether the chase is up or down an incline.

B选项中，”respondimmediately to changes” weaken hypothesis 2，重点在
“pause equally frequently”，它support beetle 的确会停下来，但频率一样暗示了它并不会休息，只支持了一半，不能选。注意题目中的
they cannot maintain their pace and must pause for a moment'srest