英语听力:自然百科 北极熊 冰上间谍 Spy_Bear—18(在线收听

 Calcium from the bones will help the mother's milk supply, but the cub needs meat to survive.

Now they have another problem. Other bears can't be trusted with small cubs. But fortunately they seem more interested in what lies beneath the surface. It looks like there is still meat to be found here, partially preserved by the cold water.
Despite her hunger, the mother can't risk joining in. But the other bears don't stay long. The mother grasps her opportunity, Her cub's survival depends on her success. The remains lie four meters down. And, at the deepest point, flesh still clings to the backbone. She emerges triumphant.
The meat must be rancid, but it's still a lifesaver. She brings some back to the shore. This is the moment the cub has been waiting for, but still he has to wait. However, unfair it seems, she must regain her strength or her cub won't survive anyway.
  原文地址:http://www.tingroom.com/lesson/zrbaike/2010/259546.html