constant volume

例句：

1. 1.The constant volume of the gas is determined by the pressure and temperature.
   气体的恒定体积由压力和温度决定。
2. 2. The constant volume of the gas is used to calculate the density.
   气体的恒定体积用于计算密度。
3. 3. The constant volume of the gas is related to the thermodynamic properties of the system.
   气体的恒定体积与系统的热力学性质有关。