在浮选机泡槽的情况下，允许短时间关闭调气盖，（）后及时打开调气盖
A、停机
B、损坏
C、液面稳定
D、放矿
参考答案：C
Nobody but doctors or nurses and those ________ by Dr. Hun ________ to enter the patient's room. [ ]
A. invited; is allowed
B. are invited; are allowed
C. being invited; allowed
D. invited; are allowed
活性染料浸染时，加入的固色剂为（）
A.元明粉
B.纯碱
C.食盐
D.碳酸氢钠
