they use oxygen far more effectively than Maiacetus. 它们利用氧气的效率远高于慈母鲸

303. The mammals had gone from tiny land animals...
     哺乳动物从微小的陆地动物
304. to being bigger than dinosaurs.
     变得比恐龙还大
305. With each giant breath,
     通过大口呼吸
306. they use oxygen far more effectively than Maiacetus.
     它们利用氧气的效率远高于慈母鲸
307. And being warm-blooded,
     而且由于是温血动物
308. their muscles are always at a temperature for maximum performance...
     肌肉始终保持在最佳性能的温度
309. ...allowing the whales to generate sustained bursts of energy.
     所以能够产生持续的能量爆发

来自《我们星球上的生命 第一季 第七集 Life on Our Planet S01E07 地球继承者》第 306 行