铁水预处理常用的脱硫剂有哪几种?
参考答案:电石粉(CaC2)、石灰石粉(CaO)、金属镁(Mg)、镁基复合脱硫剂(Mg/CaO、Mg/CaC2)、苏打粉(Na₂CO₃)
Her mother often forgets _____ the door but this morning she remembered _____ it.
A.to close…to close
B.closing … closing
C.to close …closing
D.closing … to close
胸痹总属本虚标实之证,其标实常见为下列几项,除外()。
A.气滞
B.血瘀
C.痰浊
D.阴寒
E.火邪