periodic inequality

例句：

1. 1. The temperature changes periodically throughout the day.
   温度在一天中周期性地变化。
2. 2.The cycle of life is periodic, with each stage lasting a certain amount of time.
   生命的循环是周期性的，每个阶段持续一定的时间。
3. 3. The moon's phases are periodic, repeating every 29.5 days.
   月亮的阶段是周期性的，每29.5天重复一次。