加工平面任意直线应用()。
A、点位控制数控机床；
B、点位直线控制数控机床；
C、轮廓控制数控机床；
D、闭环控制数控机床
参考答案：B
请在图中用光路图作出井底之蛙“观天”的最大范围．
I asked her whether she had done all the work herself ________ whether she had had asked sb. for help.
A．and
B．but
C．nor
D．or
