—Good afternoon, __________?The name is George Parks.

—Two letters,sir,and a postcard.

A．is there any mail for me

B．could you post these letters for me

C．what can I do for you

D．is that John speaking

对单位质量，定组成的均相流体体系，在非流动条件下有（）。

A.dH=TdS+Vdp

B.dH=SdT+Vdp

C.dH=-SdT+Vdp

D.dH=-TdS-Vdp