Supposedly, since your teacher taught you materialization, shouldn't you talk about Maxwell's relationship first?

In fact, the derivation only uses a simple formula of high number, with the emphasis on memorizing the expressions of Du, DH, DA and DG.

There are clear relationships and ideas in the Baidu library link I gave you. Those partial derivatives related to Cv and Cp really start with the definition of S.

Ps: The third formula is wrong. T2/T 1 should be changed to P2/P 1.

The first two formulas can be integrated by writing each partial derivative expression according to your thinking. The last formula can be derived from the first two formulas, and the third formula can be obtained from CP * a-cv * b.