A:分馏、干馏都是物理变化
B:127I和131I互为同素异形体
C:硫酸铜、二氧化硫都是电解质
D:盐酸、漂白粉都是混合物
There are many ____ (different) between living in a big city and living in the countryside.
宋朝时,妇女缠足的陋习逐渐传开,反映出( )