工件安装时，避免使用需要占用数控机床机时的（）方案，以便充分发挥数控机床的功效
A.装夹
B.设计
C.工艺
D.测量
参考答案：A
He is a (an) _____ grandfather. He often spends all his free time with his grandson. [ ]
A. lovely
B. loving
C. creative
碳钢中除含有铁、碳元素以外，还有少量的铬、钼、硫、磷等杂质。（）
