把“对顶角相等” 改成“如果……，那么……”的形式：_______。
如果两个角是对顶角，那么这两个角相等
“如果”后面是题设，“那么”后面是结论。
已知菱形的周长为12cm，两邻角之比为1：2，求此菱形的面积。
—Tom liked playing football when he was young .
—_____, He plays it very well.
A. So he was B. So he did C. So did he
