Listen, Richard,doing aerobics for an hour is a lot different than lifting weights.
听着, Richard,一小时的有氧运动可与举重大不相同。
This is because they had no natural enemies until the arrival of humans and therefore did not need to develop flying wings.
这是因为人类到达这里之前,这些鸟没有天敌,因此,它们不需要发育飞行的翅膀。