CH CH CH STC H2C CH 连三甲苯 偏三甲苯 均三甲苯 1,2,3-三甲苯 1,2,4-三甲苯 ,3,5-三甲苯 H3C H:0 1,2,3,4-四甲苯1,2,3,5-四甲苯1,2,4,5-四甲苯1,2,3-三甲苯 1,2,4-三甲苯 1,3,5-三甲苯 连三甲苯 偏三甲苯 均三甲苯 CH3 CH3 CH3 CH3 H3 C CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 H3 C CH3 CH3 H3 C CH3 1,2,3,4-四甲苯 1,2,3，5-四甲苯 1,2，4，5-四甲苯