A.R-Cl>R-I>R-Br B.R-Br>R-I>R-Cl C.R-I>R-Br>R-Cl D.R-I>R-Cl>R-Br
A.苯二醛 B.苯二酸 C.苯二酚 D.苯二酸酯
A.醇 B.空氣 C.酮 D.醛