①2H2(g)+O2(g)=2 H2O(1) ΔH1= -akJ/mol
②H2(g)+ O2(g)=H2O (g) ΔH2= -bkJ/mol
③C(s)+ O2(g)=CO(g) ΔH3 = -ckJ/mol
④C(s)+ O2 (g)=CO2(g) ΔH4= -dkJ/mol
下列说法正确的是( )