托福英语 学英语,练听力,上听力课堂! 注册 登录
> 托福 > 托福听力教程 > 托福听力短文 >  列表

托福听力短文 II-12-1

所属教程:托福听力短文

浏览:

gewei

随身学
扫描二维码方便学习和分享
http://online2.tingclass.net/lesson/shi0529/0008/8562/0121.mp3
http://image.tingclass.net/statics/js/2012

(WA) 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.

内容来自 听力课堂网:http://www.tingclass.net/show-8562-246810-1.html
用手机学英语,请加听力课堂微信公众号:tingclass123
用户搜索

疯狂英语 英语语法 新概念英语 走遍美国 四级听力 英语音标 英语入门 发音 美语 四级 新东方 七年级 赖世雄 zero是什么意思

  • 微信公众号:每日托福
  • [微信扫码,即可关注]
  • 关注有惊喜,经典托福资料免费送! 每天的精彩内容,不容错过。
  • 频道推荐
  • |
  • 全站推荐
  • 广播听力
  • |
  • 推荐下载
  • 网站推荐
0.093750