Are you clear _____ what has been taught in this class? That is: Is everything that has been taught

in this class clear _____ you?     [ ]

A. with; with  

B. about; about  

C. about; with  

D. about; to

临时供气作业符合（）的，作业等级上升一级。

A、临时供气时间超过48小时（含48小时）；

B、临时供气单瓶供气点数超过50个点或集中供气超过8个点；

C、节假日期间；

D、在大型活动或集会地1公里范围内；

E、天气条件恶劣