问题
选择题
Facing the dangerous situation, he was completely______.
A．at loss
B．at a loss
C．out of order
D．out of sight
答案
答案：B
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。
