在天空之城，熊的足迹。呦呦导航

　　Get to know bear cubs, Archie and Luke, in this adorable clip from the BBC Natural History Unit programme, Big Sky Bears. Their first year is full of trials and hardships in the majestic Teton Mountains in the United States. Their protective mother watches out for predators such as coyotes, mountain lions and cannibalistic bears, as she allows the cubs to learn survival techniq... (展开全部)