一质点从静止开始做匀加速直线运动，第2 s内通过的位移是3 m，则(  )

A．第2 s内的平均速度是1.5 m/s

B．物体的加速度是2 m/s²

C．前3 s内的位移是6 m

D．3 s末的速度是6 m/s

She likes to have everything in order so that she can ______ them when necessary.

A．have a hand in

B．place hands on

C．put her hands on

D．lay her hand on