—OH
CH2—
CH2
= CH
CH2COOH
—CH2COOH
COOH
CH3CH2— C—OC2H5
CH4
CH3CH3
CH3CH2CH3
CH3CH2CH2CH3
H2CO3
Na2SO4
K2HPO4
(NH4)2NO3
练习:树状分类法