benign one minute, life-threatening the next. 但天气喜怒无常

162. The calves are born well before the spring melt,
     牛犊出生在春天冰盖融化之前
163. giving them a head start when summer finally arrives.
     这样可以顺利地迎接夏天的到来
164. It must get to grips with its new ice world,
     它们必须适应这个冰雪世界
165. benign one minute, life-threatening the next.
     但天气喜怒无常
166. Even in spring, winds chill to the bone.
     即使是春天 仍然寒风彻骨
167. The calf must stay close to its mother to avoid getting lost in the sudden blizzard.
     小牛必须紧跟着母亲 才能避免在突如其来的暴风雪中迷路
168. Arctic wolves!
     北极狼

来自《行星地球 第一季 第六集 Planet Earth S01E06 冰雪世界》第 165 行