毒剂按对人员的毒害作用分哪几类？

A. They are designed to provide for the flow of small volumes of tank atmospheres caused by thermal variations in a cargo tank
B. They should operate in advance of the pressure/vacuum breakers
C. They should be kept in good working order by regular inspection and cleaning
D. All of the above

A. 专人协助扶梯
B. 专人监督使用
C. 把底部垫牢

A. 施工单位的技术负责人、编制人
B. 监理单位的总监、现场监理
C. 设计单位的绘制人、设计负责人
D. 建设单位的技术负责人、现场代表
E. 地勘单位的技术负责人