与“207×0”结果相等的算式是[ ]
A．207+0
B．207-0
C．207-207
答案：C
物体由静止开始做匀加速直线运动，第1s内的位移为2m，则第1s末的速度为______m/s，加速度为______m/s2．
He asked a lot of questions, none of ______ was easy to answer.
A．which
B．them
C．what
D．that
