C2H5COOCH3\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{COOCH}_{3}C2H5COOCH3
C2H5OH\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}C2H5OH
(C2H5)2O\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{O}(C2H5)2O
CH3COOH\mathrm{CH}_{3} \mathrm{COOH}CH3COOH