The small town is so good a place _____ many people come to visit _____ it has become well known all over the world.[ ]

A. as; that  

B. that; that

C. as; as  

D. that; as

滤池按滤池在运行周期内的滤速变化可分为（）。

A、恒速过滤和变速（减速）过滤

B、进水调节、出水调节、流量控制

C、普通（四阀）滤池、双阀滤池、无阀滤池、虹吸滤池

D、重力式滤池和压力式滤池