刀具材料中，硬度、耐磨性最高的是（）
A.硬质合金
B.陶瓷
C.立方氮化硼
D.聚晶金刚石
参考答案：D
My friend asked me _______. [ ]
A. if I will come to the party
B. that he would help me to clean the room
C. what was wrong with me
D. how should he do it next
计算机系统发展历程
