any male would struggle to stay on top. 任何雄企鹅都会拼命留在上面
brings huge quantities of food into these high rivers that normally struggle to support much life. 于是这些平常只能勉强维持众多动物生计的 高山河流终于有了提供饕餮大餐的机会
In the ascent every wing beat becomes an exhausting struggle. 上升过程中每扇一下翅膀 都得用尽全身气力
and the eagle has to struggle to control it. 金雕不得不努力控制飞行
The struggle of a giant panda mother to raise her cub 大熊猫努力养育幼崽的情景
and can make all the difference in a bear's annual struggle for survival. 直接关系到灰熊每年冬天的生存能力