constant area

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 sun's rays are constant and never change.
   太阳的光线是恒定的，永远不会改变。
3. 3.The river flows constantly, never stagnant.
   这条河流流不息，从不停滞。