在车床上不可以进行的加工有（）
A、车外圆；车锥面
B、钻孔；钻中心孔；镗孔
C、车螺纹
D、齿轮齿形加工
参考答案：D
It won’t be too long before we_____a way to smooth away these difficulties.
A．work out
B．willworkout
C．had worked out
D．are working out
一辆汽车以25m/s的速度匀速行驶，该车在20s内行驶的路程是______m．
