A．2CH4(g)＋4O2(g)===2CO2(g)＋4H2O(l) ΔH=＋890 kJ·mol^－^1

B．CH4(g)＋2O2(g)===CO2(g)＋2H2O(l) ΔH=＋890 kJ·mol^－^1

C．CH4(g)＋2O2(g)===CO2(g)＋2H2O(l) ΔH=－890 kJ·mol^－^1

D．1/2CH4(g)＋O2(g)===1/2CO2(g)＋H2O(l) ΔH=－890 kJ·mol^－^1