数控车床以主轴轴线方向为( )轴方向，刀具远离工件的方向为Z轴的正方向。
A．Z
B．X
C．Y
D．坐标
参考答案：A
I would have gone to visit him in the hospital had it been at all possible, but I_______ fully occupied the whole of last week.
A．were
B．had been
C．have been
D．was
—Where can I tie the horse?
—Oh,you can tie it to ______of the tree.
A．both
B．every
C．each
D．either
