在转化开工过程中,转化床层120℃恒温,目的是()
A、脱除转化催化剂中的结晶水
B、脱除转化催化剂中的吸附水
C、准备配蒸汽
参考答案:B
______a teacher, John thinks that his duty is to help the students to become better learners.[ ]
A. As
B. By
C. About
D. With
治疗阳痿、阴痒、湿疹、带下的药物是()
A.硫黄
B.白矾
C.续断
D.蛇床子
E.雄黄