Could you tell me _______, please?[ ]

A. that he has been to Beijing twice                    

B. what will they talk at tomorrow’s meeting

C. where they would meet at the gate of the park            

D. something about tomorrow’s weather

SF₆气体质量监督和管理的基本内容是（）。

A.新气

B.使用中气体

C.设备解体时气体

D.检测仪器及安全防护

E.生产过程