and grass that has lain dormant and frozen throughout the winter sprouts once more. 又开始发芽
but once a year they come together to have their young. 然而 每年总有一次 这些它们将会聚集在一起 繁衍后代
Thirty days after it last set, the sun rises once more on Antarctica. 南极洲的太阳在落山30天后 再次升起
the steady roar of a billion beating locust wings will once again be replaced by nothing more than the sound of the desert wind. 无数蝗虫拍打翅膀时的喧哗将不复存在 再次取代它的只是沙漠中呼啸的风声
means that desert elephants can only refill their tanks once every four or five days. 意味着沙漠里的大象 只能每隔四五天喝饱一回
It's an event that only happens once or twice a year at the most. 而且一年最多也只发生1~2次
were once part of a continuous rocky plateau. 曾经是一整块岩石高地的一部分
shows us once again how complex and surprising the underground world can be. 再一次向我们展示了地底世界 是多么的复杂和惊人