\[\begin{equation} \left \{ \begin{array}{l} T_s=5^\circ \rm{C}\\ h' = 21.02 \,\rm{kJ/kg} & h' ' = 2510.07 \,\rm{kJ/kg}\\ \end{array} \right. \end{equation}\] \[\begin{equation} \left \{ \begin{array}{l} T_s=10^\circ \rm{C}\\ h' = 42.02 \,\rm{kJ/kg} & h' ' = 2519.23 \,\rm{kJ/kg}\\ \end{array} \right. \end{equation}\] 内挿法により，$T_s=8^\circ \rm{C}$では， \[ \begin{align} h' &=21.02+\frac{42.02-21.02}{10-5}\times (8-5) \\ &=33.62 \,\rm{kJ/kg} \end{align} \] \[ \begin{align} h' ' &=2510.07+\frac{2519.23-2510.07}{10-5}\times (8-5) \\ &=2515.57 \,\rm{kJ/kg} \end{align} \]