For billions of years, 数十亿年来

1. For billions of years,
   数十亿年来
2. much of our world was fiercely inhospitable...
   我们世界的许多地方 都极不适宜生存
3. ...ravaged by the elements and the forces of nature.
   这些地方遭到自然因素和力量的摧残
4. But this is the story of what was happening beneath the waves.
   但本集将讲述的是海浪下发生的故事

来自《我们星球上的生命 第一季 第二集 Life on Our Planet S01E02 第一前线》第 1 行