B2O3\mathrm{B}_{2} \mathrm{O}_{3}B2O3
BeO\mathrm{BeO}BeO
P2O5\mathrm{P}_{2} \mathrm{O}_{5}P2O5
Cl2O7\mathrm{Cl}_{2} \mathrm{O}_{7}Cl2O7