the tendancy of aging

• 人口老龄化

the tendancy of aging的用法和样例：

例句

1. China's population is aging at unprecedented levels.
   使中国人口老龄化达到了前所未有的水平。
2. Though the US is not immune to population aging, its higher level of fertility combined with immigration gives it an enormous advantage.
   美国并非不会受到人口老龄化的影响，但高水平的生育率加大量的移民给其带来巨大的优势。