Animal Navigation System托福聽力原文翻譯及問題答案

Animal Navigation System托福聽力原文翻譯及問題答案

一、Animal Navigation System托福聽力原文：

NARRATOR:Listen to part of a lecture in an animal behavior class.FEMALE PROFESSOR:Before we leave the topic of animal navigation,let's look at one more species and how it finds its way through its environment.The species we'll look at is the blind mole rat.Blind mole rats are interesting in terms of navigation because they live entirely in the dark-in elaborate underground tunnel systems.So how do blind mole rats find their way around in these complicated tunnels?Well,for some time we've known that blind mole rats use some combination of two different navigation systems.

Um,one system relies on their sense of time and their ability to remember underground landmarks.For example,let's say a mole rat wants to find its way through its tunnel system back to its nest where it sleeps.Well,it goes along.Then it feels some hard stones or a tree root under its feet and it basically says to itself."Ok,here is where I took a left."And then it might remember how long it took to get to the next turn and so forth.The mole rat goes straight or turns based on what it remembers having sensed along the way on previous trips and the time it took between turns.Now,the other navigation system for the mole rat relies on Earth's magnetic field.Mole rats have the ability to sense the magnetic field and use it to orient themselves directionally.But until recently scientists weren't sure about the role of these two different systems.

Recently a team of researchers conducted an experiment to answer that question.Do these two navigation systems play different roles?What they did was they designed a special structure that very closely resembles a blind mole rat's tunnel system,which looks like a bicycle wheel,a central hub with multiple spokes radiating outward.

Now this turned out to be quite important.Earlier experiments have used a more generic habitat,basically a wide open circle,which was originally designed to test magnetic navigation in other animals.That design led to inconclusive results with mole rats.

Now,with their bicycle wheel tunnel system the researchers were able to vary the distance that the mole rats travel between their nest and their food source by creating long routes and short routes.In each trial,the mole rats started out in their nest,went to the food source and then had to find their way back home,back to the nest.To determine which navigation system they were using,the researchers tested the animals under two different conditions.

First,the mole rats were tested under conditions of normal magnetism for both the trip to the food and the trip home.And under these normal conditions,they all followed their original route back home,regardless of the length of the trip to the food source.

Then in the second part of the experiment,the magnetic field was altered but only for the trip home,a specially constructed set of magnets was used to shift the magnetic field around the habitat 90 degrees eastward.The researchers wanted to see how the mole rats responded to this shift.Well,it turns out that the magnetic shift had no impact on the return route of the blind mole rats after a short trip.They returned to the point where they had started from.

But after a longer trip,they took a totally different route:one that led them nine degrees east of the nest.Essentially they got lost.This was strong evidence that blind mole rats use magnetic navigation only for longer trips.So why two navigation systems?one for long trips and one for short trips?

Well,for now we can only speculate,but we think that when mole rats rely on the first system,using underground landmarks or their sense of time,well,they make small mistakes here and there.On a short trip,this doesn't matter much.The trip is short,so they can't make many mistakes.

But on a long trip,well,there are lots of opportunities to make small mistakes,and small mistakes can add up,leading the mole rat far from where it wants to be.So on a long trip,a magnetic navigation system is better,more useful,since earth's magnetic field is stable,a constant,a more reliable indicator of direction.

二、Animal Navigation System托福聽力中文翻譯：

旁白：在動物行為課上聽一部分講座。女教授：在我們離開動物導航的話題之前，讓我們再看一個物種，看看它是如何在環(huán)境中找到自己的路的。我們要研究的物種是盲鼴鼠。盲鼴鼠在導航方面很有趣，因為它們完全生活在黑暗中，生活在復雜的地下隧道系統(tǒng)中。那幺，盲鼴鼠是如何在這些復雜的隧道中找到自己的路的呢？一段時間以來，我們知道盲鼴鼠使用兩種不同導航系統(tǒng)的組合。

嗯，一個系統(tǒng)依賴于他們的時間感和記憶地下地標的能力。例如，假設(shè)一只鼴鼠想通過它的隧道系統(tǒng)找到自己的路，回到它睡覺的巢穴。嗯，它一直在發(fā)展。然后它感覺到腳下有一些堅硬的石頭或樹根，它基本上會自言自語。“好吧，這是我左轉(zhuǎn)的地方?！比缓笏赡軙浀玫较乱粋€轉(zhuǎn)彎需要多長時間，等等。鼴鼠根據(jù)它記憶中在之前的旅程中所感知到的東西和它在兩次轉(zhuǎn)彎之間所用的時間，走直線或轉(zhuǎn)彎?，F(xiàn)在，鼴鼠的另一個導航系統(tǒng)依賴于地球磁場。鼴鼠有能力感知磁場并利用磁場定向。但直到最近，科學家們還不確定這兩種不同系統(tǒng)的作用。

最近，一組研究人員進行了一項實驗來回答這個問題。這兩個導航系統(tǒng)的作用不同嗎？他們所做的是設(shè)計了一種特殊的結(jié)構(gòu)，非常類似于盲鼴鼠的隧道系統(tǒng)，它看起來像一個自行車車輪，一個中心輪轂，多個輻條向外輻射。

現(xiàn)在這證明是非常重要的。早期的實驗使用了更通用的棲息地，基本上是一個開闊的圓，最初設(shè)計用于測試其他動物的磁導航。該設(shè)計導致了對鼴鼠的非決定性結(jié)果。

現(xiàn)在，通過自行車輪隧道系統(tǒng)，研究人員能夠通過創(chuàng)建長路線和短路線來改變鼴鼠在巢穴和食物來源之間的距離。在每一次試驗中，鼴鼠都從巢穴開始，找到食物來源，然后必須找到回家的路，回到巢穴。為了確定他們使用的是哪種導航系統(tǒng)，研究人員在兩種不同的條件下測試了這些動物。

首先，在正常磁性條件下對鼴鼠進行食物和回家的測試。在這些正常的條件下，他們都按照原來的路線回家，不管去食物來源的路程有多長。

然后，在實驗的第二部分，改變了磁場，但僅在回家的路上，使用了一組特殊構(gòu)造的磁鐵，將棲息地周圍的磁場向東移動90度。研究人員想知道鼴鼠對這種變化的反應。事實證明，磁位移對盲鼴鼠短暫旅行后的返回路線沒有影響。他們回到了起點。

但經(jīng)過一次長途旅行后，它們選擇了一條完全不同的路線：一條通向鳥巢以東九度的路線。基本上他們迷路了。這有力地證明，盲鼴鼠只在長途旅行中使用磁導航。那么，為什么有兩個導航系統(tǒng)？一個用于長途旅行，一個用于短途旅行？

嗯，現(xiàn)在我們只能推測，但我們認為當鼴鼠依靠第一個系統(tǒng)，利用地下地標或他們的時間感時，他們會犯一些小錯誤。在短途旅行中，這并不重要。旅程很短，所以他們不會犯很多錯誤。

但是在長途旅行中，會有很多機會犯小錯誤，小錯誤加起來會導致鼴鼠遠離它想去的地方。所以在長途旅行中，磁導航系統(tǒng)更好，更有用，因為地球磁場是穩(wěn)定的，恒定的，更可靠的方向指示器。

三、Animal Navigation System托福聽力問題：

Q1:1.What is the lecture mainly about?

A.The structure of the blind mole rats'underground tunnel system

B.How blind mole rates find their way back to their nests

C.Whether some animals use Earth's magnetic field for navigation

D.Whether blind mole rats have more than one navigation system

Q2:2.Why does the professor mention tree roots and rocks?

A.To emphasize the blind mole rat's need for two navigation systems

B.To explain one reason why blind mole rats get lost

C.To give examples of landmarks used by the blind mole rat

D.To describe the materials the blind mole rat uses to build its nest

Q3:3.In discussing the experiment,why does the professor refer to a generic habitat?

A.To prevent a misunderstanding about blind mole rats'tunnel systems

B.To indicate how the researchers found the animals for the experiment

C.To describe similarities between blind mole rats'natural habitat and those of other animals

D.To emphasize the importance of habitat design to the success of the experiment

Q4:4.What did the research team modify in the second part of their experiment?

A.They removed the food from the habitat.

B.They increased the distance between the nest and the food source.

C.They changed the magnetic field around the habitat.

D.They shifted the location of obstacles in the tunnels.

Q5:5.According to the professor,what factor governs which navigation system the blind mole rat uses in a given situation?

A.The distance traveled

B.The direction of travel

C.The complexity of the tunnel system

D.The presence or absence of landmarks

Q6:6.What does the professor imply when she explains why blind mole rats use two navigation systems?

A.One system is more accurate than the other for long trips.

B.One system takes more time to use than the other one does.

C.Individual blind mole rats have a preference for on system or the other.

D.Animals usually do not rely on only one navigation system for long trips.

四、Animal Navigation System托福聽力答案：

A1:正確答案：B

A2:正確答案：C

A3:正確答案：D

A4:正確答案：C

A5:正確答案：A

A6:正確答案：A

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