传真机在使用前的准备工作是______、功能设定、选择清晰度和对比度。
参考答案：安装记录纸
A．前4min乙同学速度比甲同学速度大
B．甲同学做匀速直线运动的速度是0.5m/s
C．乙同学第4min后仍做匀速直线运动
D．甲、乙同学相遇时距起点240m
______________absent from competition for two seasons，Shen Xue and Zhao Hongbo still had
the right feeling on the ice .
A．As long as
B．Even if
C．In case
D．No matter
