数控加工程序是从（）输入数控机床用于加工的程序（软件）。
A、内部
B、外部
C、内部和外部
D、网上
参考答案：B
— Mrs.Smith,please teach me how to draw on the computer today.
—Oh,no. ____.You have to get familiar with the keyboard first.
A．It is never too old to learn
B．Think twice before you do
C．Learn to walk before you run
D．One today is worth two tomorrows
脊神经前、后根的合成部位是（）
A.椎管
B.椎孔
C.椎间孔
D.横突孔
