英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—16（在线收听） |
But it's not enough. For a hunting bear, it doesn't get much worse than this. The seal could hardly fail to notice. But this battle-hardened seal is in no rush. Finally he gains some purchase, he's back in the game. He still believes he's in with a chance. He can charge at 25 miles per hour. But bears usually wait until they're 30 meters away, this one started at 300. She has all the time in the world to escape. Only the bears unexpected dunking in the ice could explain such an amateur performance. The ice is now so thin. It only supports the weight of lighter cubs, leaving the mother struggling. This is a sign that the mother must head north to the more permanent icecap as quickly as possible. But a combination of wind and current destroys her best-laid plan. A sudden swell turns ice into open ocean. The cubs are too young to swim long distances safely. |
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