______ difficult the problem was, he tried his best to solve it.

A．No matter

B．Although

C．Whatever

D．However

在路基内埋设电缆时，电缆应从路堤外或路堑顶外通过。如遇过渡短经路从路肩或路堤边坡上通过时，应进行结构设计，并不得损坏原有排水、防护和加固设备。