预防尿酸盐结石可服用（）
A.氧化镁或维生素B
B.氯化铵
C.碳酸氢钠
D.氯化钾
E.别嘌呤醇
参考答案：C
Could you give me a hand? It seems that my strength has _________.
A．used up
B．been given out
C．run out
D．been run out
简述低碳钢、中碳钢和高碳钢的划分标准及其各自的性能特点。
