运动员参加110米栏比赛,11秒末到达终点的速度为12m/s,则全程的平均速度是( )
A:10 m/s
B:11 m/s
C:6 m/s
D:12 m/s
—Sunny but cold.
-- It's difficult for the village children to cross the river for school.
-- I think a bridge ________ over the river.