theart.那；这；这些；那些adv.（用于比较级前）更加；用于最高级前；(用于形容词、副词比较级前)越 ... 越 ...thermo-colorn.热变色

1. Aging has become a social problem.
   老龄化已成为一个社会问题。
2. 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。