H2O\mathrm{H}_{2} \mathrm{O}H2O
HCHO\mathrm{HCHO}HCHO
CH3−CHO\mathrm{CH}_{3}-\mathrm{CHO}CH3−CHO
CH3−CO−CH3\mathrm{CH}_{3}-\mathrm{CO}-\mathrm{CH}_{3}CH3−CO−CH3