Under no circumstances _______ the difficulties when they were on an expedition to the Antarctic．

A．they gave way to

B．did they give way to

C．they had given way to

D．had they given way to

《安规》规定，中断工作连续（）个月以上而仍继续担任接触网运行和检修工作的人员，上岗前要进行安全考试。