《室外排水设计规范》(GB 50014—2006)规定，管道跌水水头为( )m时，宜设跌水井。

A．2.0～3.0

B．1.0～2.0

C．1.5～2.0

D．2.5～3.0

Please        talk in class.[ ]

A.don't

B.doesn't

C.isn't

D.aren't