CNC系统为典型加工工步所编制的，可以多次循环加工的功能是（）功能。
A.补尝
B.固定循环
C.图形显示
D.通信
参考答案：B
When your child wakes up in the morning, he should know that his daily ____ includes going to school, lunch and homework.
A．routine
B．destination
C．requirement
D．conservation
北京城“胡同”这个名称，始自元大都时期。（）
