数控车床的（）通常设在主轴端面与轴线的相交点。
A、机床参考点
B、机床坐标原点
C、工件坐系零点
D、换刀点
参考答案：B
He didn't bring his pen with him; he can use a pencil ____. [ ]
A. too
B. also
C. instead
D. yet
髓外造血
