在开环数控系统中，坐标轴运动的速度是通过控制步进电机的走步时间间隔来实现的。
参考答案：对
2x2y-8xy+8y
Helen couldn’t go to France after all. That’s too bad. I’m sure she would have enjoyed it if _____.
A．she’s gone
B．she’ll go
C．she’d gone
D．she’d go
