natural ageing

例句：

1. 1. The elderly often face challenges due to natural ageing.
   老年人往往因自然老化而面临挑战。
2. 2.With the passage of time, many species undergo natural ageing.
   随着时间的推移，许多物种会经历自然老化。
3. 3. As we age, our bodies undergo natural ageing processes that can affect our health.
   随着年龄的增长，我们的身体状况会经历自然老化过程，这可能会影响我们的健康。