There were many, many nightingales, and how then should he find out which was his Jorinda?
有许许多多只夜莺，那他怎么知道哪只是他的约丽丹呢？
2
To obtain empirical data regarding the energy costs of singing, Thomas examined the relationship between song rate and overnight changes in body mass of male nightingales.
为了获得有关唱歌能量消耗的经验数据，托马斯研究了鸣声率与雄性夜莺在夜间的体重变化之间的关系。
3
The strategic regulation of evening body reserves is also likely to incur additional costs, as nightingales must spend more time foraging in order to build up larger body reserves.