英语听力：探索发现 2012-11-28 美洲大平原 American Serengeti—14（在线收听） |
13,000 years ago, the ice age cheetah was the pronghorn's greatest enemy. And pronghorn would have needed all their amazing speed. The American cheetah was larger than its African cousin. But it had the same Achilles' heel. A cheetah's high-performance muscles overheat in minutes, and unlike pronghorn, they can't switch to cruising speed. So if the pronghorn managed to outrun the cheetah for the crucial first few hundred meters, it would probably survive. The cheetah hasn't roamed the plains of North America for thousands of years, but pronghorn are still prime for the chase. Other extinct links to Africa had been found in caves steep in the Ozark Mountains of Missouri. Preserved in mud were huge prints recreated here, more than 18 centimetres wide. What could have made them? They belonged to another ice age cat, the top cat of the plains, a lion. |
| 原文地址：http://www.tingroom.com/lesson/yytltsfx/2012/244992.html |