11.壓力0.5MPa時飽和水的比焓640.1 kJ/Kg，飽和水蒸汽的比焓2748.1 kJ/Kg。若鍋爐壓力為0.5MPa時水蒸汽的比焓為2452.98 kJ/Kg，則其乾度為：
(A)0.66
(B)0.76
(C)0.86
(D)0.96