Vainest
a. 自负的( vain的最高级 ); 爱慕虚荣的; 徒劳的; 无用的
🗣️ 情景例句
Lovely!
太可爱了！
There is no royal road to learning.
治学无坦途。
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。