Jellyfish have a complex and interesting life cycle.

水母的生存期既复杂又有趣。

Milankovitch wondered if there might be a relationship between these complex cycles and the comings and goings of ice ages.

米兰柯维契觉得，这些周期性的复杂变化与冰川期的产生和消退也许存在某种关系。