So for the reversible process, the work done is the integral under the pressure volume state function, the function of state.

对可逆过程，做的功,是压强体积态函数曲线下，的积分面积。

麻省理工公开课 - 热力学与动力学课程节选

If it's a reversible process, we know the work is the area under the curve.

对可逆过程，功等于p-V图上。

麻省理工公开课 - 热力学与动力学课程节选