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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-performan
探索与发现2012年
By Anjana Pasricha New Delhi 18 July 2006 India has deferred peace talks with Pakistan in the wake of the deadly train bombings in Mumbai, accusing its neighbor of abetting terror attacks in India. The bomb blasts have cast a shadow over a two-year
2006年VOA标准英语（七月）
The site was once a spring-fed pond, full of water. Mammoths were tempted in to drink. But when they tried to climb back out, the banks were steep and slippery. Just like the short-faced bear imprisoned underground, some became trapped. Scavengers wo
探索与发现2012年
The store of pollen paints a picture of the plains of 13,000 years ago, a picture that looks very different from the open prairie grassland of today. But why did this region look so different back then? The ice sheets to the north, although retreatin
探索与发现2012年
The Osage orange seeds were carried far across the plains, before being deposited, pre-packed in their fertilizer growbags, ready to take root. As the ice age waned, the milder climate and the mixed vegetation meant the plains were able to support a
探索与发现2012年
As North America emerged from the grip of the last ice age, the door was opened to outsiders for the very first time. As these early immigrants pushed their way south, they found themselves in a land of an unimaginable opportunity, overflowing with g
探索与发现2012年