托福听力荟萃 42（在线收听）

If you liked the colorful animals we just saw, you're going to love these next animals. Frogs. You might not normally think of frogs as being colorful, but these frogs definitely are. They are the dart-poison frogs of Central and South America. Look at their striking colors --- often yellow with black ______ or deep blue with black ______.

Beyond being nice to look at, these markings have a _____.They warn predators that these frogs are ______.When threatened, these frogs secrete a _______through their skin that would easily kill whatever animal might try to eat them. Their bright colors communicate this, and so most animals tend not to hunt them.

Now, speaking of hunting, for centuries these frogs were sought after by hunters. As you might think, the hunters didn't want to eat the frogs, but rather, they captured them for their poison. They would add the poison to the tips of their hunting arrows --- of course, nowadays most hunters use guns.

These days dart-poison frogs are of less interest to hunters than to medical researchers. Researchers believe that they can make new heart medicine from the poison, because it acts as a stimulant on the body's nervous system. Researchers think they could use it to stimulate a weak heart.

There is, however, a problem with doing research on these frogs. Those that are caught in the wind will produce their poison until they die. However, those that are born in captivity, like the ones you see here, will not produce any poison at all.

【填空答案】

1.stripes n. 条子布；条纹布（stripe复数形式）

2.spots n. 斑点（spot的复数）；插播广告；花点布，点子花纹棉布；置球点

3.purpose n. 目的；用途；意志

4.poisonous adj. 有毒的；恶毒的；讨厌的

5.substance n. 物质；实质；资产；主旨

【听力原文】

If you liked the colorful animals we just saw, you're going to love these next animals. Frogs. You might not normally think of frogs as being colorful, but these frogs definitely are. They are the dart-poison frogs of Central and South America. Look at their striking colors --- often yellow with black stripes or deep blue with black spots.

Beyond being nice to look at, these markings have a purpose. They warn predators that these frogs are poisonous. When threatened, these frogs secrete a substance through their skin that would easily kill whatever animal might try to eat them. Their bright colors communicate this, and so most animals tend not to hunt them.

Now, speaking of hunting, for centuries these frogs were sought after by hunters. As you might think, the hunters didn't want to eat the frogs, but rather, they captured them for their poison. They would add the poison to the tips of their hunting arrows --- of course, nowadays most hunters use guns.

These days dart-poison frogs are of less interest to hunters than to medical researchers. Researchers believe that they can make new heart medicine from the poison, because it acts as a stimulant on the body's nervous system. Researchers think they could use it to stimulate a weak heart.

There is, however, a problem with doing research on these frogs. Those that are caught in the wind will produce their poison until they die. However, those that are born in captivity, like the ones you see here, will not produce any poison at all.

【参考译文】

如果您喜欢我们刚才看到的五颜六色的动物，你会喜欢这些动物。青蛙。通常你可能不认为作为丰富多彩的青蛙，但肯定是这些青蛙。他们是中美洲和南美洲的毒镖青蛙。看看他们醒目的颜色---经常黄色与黑色条纹，或有黑色斑点的深蓝色。

除了好看，这些标记有一个目的。他们警告捕食者，这些青蛙是有毒的。受到威胁时，这些青蛙会分泌一种物质通过他们的皮肤会很容易地杀死任何动物可以尝试吃。其鲜艳的色彩沟通这一点，所以大多数动物往往不能追捕他们。

现在，狩猎，几个世纪以来，这些青蛙后寻求猎人。正如你可能会认为，猎人们不想吃青蛙，而是，他们捕捉到他们的毒药。他们将加入毒药，他们的狩猎箭头提示---当然，时下最猎人使用枪支。

这些天镖毒蛙是扣除利息，而不是医学研究人员的猎人。研究人员认为，他们可以使新的心脏药物的毒，因为它作为一种对人体的中枢神经系统的兴奋剂行为。研究人员认为，他们可以用它来刺激心脏衰弱。

有，然而，与这些青蛙做研究的问题。那些在风中捕获的会产生他们，直到他们死去的毒药。然而，那些在圈养出生的，你在这里看到的一样，不会产生任何毒。