CH3COOH\mathrm{CH}_{3} \mathrm{COOH}CH3COOH
H2C=CH2\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}H2C=CH2
HC≡CH\mathrm{HC} \equiv \mathrm{CH}HC≡CH
CH3CHO\mathrm{CH}_{3} \mathrm{CHO}CH3CHO