That is where she hunts for the seal she needs to feed her cubs. 而母熊则需要在那里捕杀海豹 喂养幼熊

42. The spring sun brings warmth
    春天的太阳带来了温暖
43. but also a problem for the mother.
    但对母熊而言却是一个问题
44. It starts to melt the sea ice.
    海面的冰层开始融化
45. That is where she hunts for the seal she needs to feed her cubs.
    而母熊则需要在那里捕杀海豹 喂养幼熊
46. And she must get there before the ice breaks up.
    因此它必须在冰层破碎之前到达那里
47. For now though it's still minus thirty degrees
    而现在的气温仍然有-30℃
48. and the cubs must have the shelter of the den.
    熊崽们必须回到洞中避寒

来自《行星地球 第一季 第一集 Planet Earth S01E01 从北极到南极》第 45 行