下列热化学方程式书写正确的是( )B.H2(g)+1/2O2(g)===H2O(l) ΔH=-285.8 kJ·mol-1C.2H2(g)+O2(g)===2H2O(l) ΔH=-571.6 kJD.C(s)+O2(g)===CO2(g) ΔH=+393.5 kJ·mol-1