Facing the dangerous situation, he was pletely .
A. at loss
B. at a loss
C. out of order
D. out of sight
网友回答
A. at loss
(答案→)B. at a loss
C. out of order
D. out of sight
解析：本题考查介词短语。句意: 面对危险的局面，他完全不知怎么办。at a loss不知所措；无计可施；out of order出故障的；out of sight在视野外。结合句意可知选B。