— Thank you very much for helping me to solve the problem.

— _____. 

A．Don't mention it

B．With pleasure

C．That's right

D．You said it

下列四种滤池中，滤速一段发生变化的滤池是（）

A.普通快滤池

B.虹吸滤池

C.无阀滤池

D.移动罩滤池