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prep的一题

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楼主
发表于 2007-8-4 08:29:00 | 只看该作者

prep的一题

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 can not maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while runninn, tiger beetles are unable to process theresulting 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 hypothsis and undermine the other?

The key is:

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.

 谁能帮忙解释一下这题啊?

沙发
发表于 2007-8-4 09:25:00 | 只看该作者

否定了第二个观点。支持第一个观点。

观点一:beetles为了保持速度攻击前要休息下。

观点二:beetles是因为run的速度太快导致blind,所以停下来为了获得visual information

答案说:beetle保持固定时间的停顿,即使当insect马上要飞走了,beetle还是在pause过后才增加速度。

如果它是为了能看得见,那么就不必停顿fixed pause啦,看到直接攻击就行了因为人家都要飞走了你还保持fixed time pause 不是傻嘛?只能说明它是为了保持速度,所以只有这样~~~

open to discuss. personal view.

板凳
发表于 2007-8-4 09:33:00 | 只看该作者

加强第一个,削弱第二个:第二个假设说when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause.速度已经快的看不见东东了,如果此假设确实成立,那就是说不能再快了.可是答案说 when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause把速度加到比先前还快了,不就是直接的削弱了?

第一个假设说是保持不了PACE,必须PAUSE一会,选项虽然没有完全讲保持不了PACE,但是确实讲到了PAUSES中间的INTERVAL,也就是说存在着休息时间了.支持题的选项本身是不需要必要性的,没有假设题那样严格;这样的一个选项还是有支持作用的.

个人意见,欢迎讨论指正!

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