A:were; wa
B:was; were
C:was; wa
D:were; were
如图,在平面直角坐标系xOy中,△ABC与△A′B′C′顶点的横、纵坐标都是整数.若△ABC与△A′B′C′是位似图形,则位似中心的坐标是____ .
甲、乙两小车同时同地同方向做匀速直线运动,它们的s﹣t图象如图所示,由图象可知( )