A:汽油挥发,酒精燃烧
B:食物腐烂,钢铁生锈
C:蜡烛燃烧,铁铸成锅
D:水分蒸发,滴水成冰
两个同心圆的半径之比为3:5,AB是大圆的直径,大圆的弦BC与小圆相切,若AC=12,那么BC=( )
We're going to have the school party _______ Sunday afternoon.