单项选择题
A.RCOOR B.RCOR C.RCOX D.(RCO)2O
A.羧酸硫酸酯 B.羧酸吡啶酯 C.羧酸三硝基苯 D.羧酸异丙烯酯
A.六元环>七元环>五元环 B.六元环>五元环>七元环 C.五元环>七元环>六元环 D.七元环>六元环>五元环