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。

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And the equation of state, pressure versus volume at constant temperature, is going to have some form, let's just draw it in there like that.

系统的态函数，恒温下压强比体积，变化曲线，就像这样。

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