Quite well in the important exam , he came back home,    and smiling.

A．Having done; relaxed

B．having done ; relaxing

C．having been done ; relaxing

D．Done; relaxed

适用于流硫层，黏土质砂土，砂质黏土层及胶结松散的砾，卵石层的下沉方法是( )。

A．人工挖土法

B．排水下沉

C．水枪冲土法

D．抓斗挖土法