炉渣碱度的高低对（）反应有较大的影响。
A.钢渣界面过程
B.去除磷硫效果
C.钢液脱气
D.冶金质量
参考答案：B
_____, the population of China is the largest in the world. [ ]
A. It is known that
B. As is well known
C. Which is well known
D. We all know that
合并急性左心衰竭的阵发性室上性心动过速，最佳治疗是（）
A.静脉注射维拉帕米
B.Valsalva动作
C.直流电复律
D.置入起搏器
E.射频消融术
