—Do you want to _____ at the meeting?  

—No, I have nothing to _____. [ ]

A. say, speak        

B. tell, talk        

C. say, say      

D. speak, say

污水在UASB反应器中的上升流速要控制在（），过高会使出水中悬浮物的含量增高；过低则起不到水力搅拌的作用。

A.1~2m/h

B.2~3m/h

C.3~4m/h

D.4~5m/h