His father got him a jib in a bank but soon it became clear ______ he was not fit for that kind of work .

A．that

B．why

C．what

D．whether

下列对路基地下水排水设施的施工要点的叙述中，正确的是( )。

A．渗井的上层不透水范围内宜填碎石或卵石

B．设在低洼地带或天然沟谷处的暗沟(管)，宜沿路线方向布置

C．检查井一般采用圆形，内径不小于1.0m，在井壁处的渗沟底应高出进底0.3～0.4m，井底铺一层厚0.1～0.2m的混凝土

D．渗沟宜从上游向下游开挖，开挖作业面应根据土质选用合理的支撑形式，并应随挖随支撑、及时回填，不可暴露太久