设备的工作精度标准是用来代替衡量机床（）精度的标准。
A.静态
B.动态
C.几何
D.传动
参考答案：B
On stepping into his room he was astonished to find the floor covered with
looked like tiny insects .
A．that
B．something
C．what
D．anything
两球A、B在光滑水平面上沿同一直线，同一方向运动，mA=1kg，mB=2kg，vA=6m/s，vB=2m/s．当A追上B并发生碰撞后，两球A、B速度的可能值是（ ）
A．vA′=5 m/s，vB′=2.5 m/s
B．vA′=2 m/s，vB′=4 m/s
C．vA′=-4 m/s，vB′=7 m/s
D．vA′=7 m/s，vB′=1.5 m/s
