—Excuse me, what can I do for you?

—Yes. I'd like to place ________ advertisement for ________ used car in your paper.[ ]

A. the; a              

B. an; /            

C. an; a              

D. /; the

冲击成孔灌注桩施工中遇孤石时应（）。

A.采用低锤密击法施工 

B.低锤冲击或间断冲击 

C.回填片石后重新冲孔 

D.采用预爆或高低冲程交替冲击