精矿中所含某种金属、非金属或其它有用组分的量与精矿量的百分比称为（）。
参考答案：精矿品位
— How about your journey to Mount Emei?
— Everything was wonderful except that our car ____ twice on the way. [ ]
A. slowed down
B. broke down
C. got down
D. put down
胎儿先露部指示点与母体骨盆的关系（）
A.胎方位
B.胎先露
C.胎产式
D.骨盆轴
E.产道
