—I'm sorry. There was too much traffic on the road. —Don’t be late again. The meeting for 15 minutes.
A:has begun
B:has stopped
C:has been on
D:has finished
下面关于生态系统的说法中,错误的是( )
甲、乙两质点同时、同地点向同一方向作直线运动,它们的v﹣t图象如图所示,则( )