Every student and every teacher _______. [ ]

A. are going to attend the meeting  

B. have attended the meeting

C. has attended the meeting     

D. is attended the meeting

煨管装砂应干燥，并应自（）均匀地敲击管壁，且管壁表面不能留有明显的凹痕。

A.中部

B.下部

C.上部

D.上下