2. 外语
  3. In this question, you will listen to a lecture. Then you will be asked to summarize important information from the lecture. Afte

In this question, you will listen to a lecture. Then you will be asked to summarize important information from the lecture. Afte

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问题     In this question, you will listen to a lecture. Then you will be asked to summarize important information from the lecture. After the question, you will have 20 seconds to prepare your response and 60 seconds to speak.
    Now listen to part of a talk in a biology class.

    Question
    Using points and examples from the talk, explain the factors that cause beavers to build dams.
Everyone knows that beavers build dams. And they have a good reason to. Dams are the source of their protection and food. By increasing the volume of water in their habitat, they increase the area in which they can move around safely and increase the amount of aquatic plant life on which they feed. Scientists wondered about the mechanism by which beavers build their dams. How do they choose the location? Do they consider the environment from an engineer’s perspective, or is their behavior strictly instinctual?
    In one experiment, researchers set up loudspeakers around a beaver habitat and played the sound of running water. Consistently, they found the speakers buried under mounds of sticks and mud, which muted the sound. In some cases, beavers built dams around speakers even when there was no water in the area. These results led biologists to conclude that it was the sound of rushing water that stimulated the dam-building response. However, subsequent experimentation showed that some beaver communities did not respond right away to the sound of rushing water. Only after considerable time passed did these beavers get around to piling up material around the speakers. This hesitation suggests that beavers have other considerations for building.
    In other experiments, ah, let’s see, there were drainpipes installed, bypassing the dams. Even when the pipes were set low in the water, taking in and releasing water far from the dams, the beavers found them and clogged them up with debris. This means that sound was not a factor in these cases. Water intake and release occurred underwater. Here’s another interesting behavior. During flooding, beavers allow water to run and do not build up their dams. These behaviors indicate that beavers do have some kind of understanding of other factors--perhaps water level, perhaps threat to food supply--and that they are not instinctively responding to just a sound stimulus.
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答案 Experimenters wanted to find out how beavers knew where to build dams. They wanted to know if the building behavior was some kind of simple instinct or some more sophisticated understanding of the environment. At first, it seemed that the sound of running water was causing instinctive response because the beavers were building on top of speakers making the sound. But sometimes they didn’t respond to the sound right away, and in some cases they allowed running water when it was beneficial to them. Also, the beavers blocked drainpipes that made no sound. So the beavers were not responding automatically to just the sound. Because of these reasons, the beavers probably have some kind of understanding about their environment.
解析   这是一道收听特定领域的相关内容，就讲座提到的概念和事例归纳讲座要点的题目。讲座的内容可能会涉及自然科学、人文、社会的各个学术领域。但是这类题型不会要求考生具备相应的专业知识和了解相应的专业概念，题目多为一般常识范围内可理解的内容。因此要求考生具备完整的归纳课文要点、用自己的语言进行整理的能力。
    参考答案说明了关于河狸修堤坝的相关实验内容。首先，河狸在发出河水声音的地方周围修堤坝，从这一实验内容看，水的声音是河狸修堤坝的原因之一。此外，讲座还完整地整理了河狸修堤坝原因中水声以外的其他要素。虽然河狸听到水声后有修堤坝的行为，但是它们不是立刻就修堤坝，而是在过了一段时间后才开始。而且在对它们有利的情况下，它们会让水自然流走。但是没有水声时，它们还会阻止水流。因此，可将上述主要内容整理如下：
    1．河狸修堤坝有很多原因；
    2．其中最重要的原因是声音；
    3．但是，不是只要有声音，河狸就会有反应；有出现声音河狸也不立即反应的情况，还有即使没有声音也要阻止水流的情况，还有让水流过的情况。
    4．因此，对河狸修堤坝来说，除了声音以外，还有其他原因存在。
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