constant of friction

例句：

1. 1.The temperature is constant throughout the day.
   温度在整个一天中都是恒定的。
2. 2. The river flows steadily through the valley.
   这条河平稳地流过山谷。
3. 3. The sun's position remains constant throughout the year.
   太阳的位置在整个一年中保持不变。