On the other hand, temperature, volume and pressure are variables that are much easier in the lab to keep constant.

另一方面，温度，体积和压强,在实验室中比较容易保持恒定。

麻省理工公开课 - 热力学与动力学课程节选

I take V1 to V2 first, keeping the pressure constant at p1, then I take p1 to p2 keeping the volume constant V2 at V2. Let's call this path 1.

容易计算的路径，第一条路径，是首先保持压强不变,体积从V1压缩到。

麻省理工公开课 - 热力学与动力学课程节选