英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—13

 If it hasn't already been seen, that is. The bears at the whale carcass are in food heaven, but their peace is about to be shattered. This male heavyweight prefers to eat alone. He is bigger than the other bears and likes to throw his weight around. This is no time for heroics. The mother tries to guide her offspring away. But the young bear is an easy target. The male could kill with just one bite. The youngster daren't turn his back. But despite the male's persistence¹, he seems to be just teaching the young upstart a lesson. Reunited with his mother, she appears to scold him. Authority established, the male is now king of the carcass. Back at the kill site, the family finally steal a meal.

1 persistence   

n.坚持，持续，存留

参考例句：

• The persistence of a cough in his daughter puzzled him.他女儿持续的咳嗽把他难住了。
• He achieved success through dogged persistence.他靠着坚持不懈取得了成功。