________________________ (在紧急情况下保持镇静) and knowing what to do can mean the difference between life and death. (calm)

在紧急情况下________

遇到紧急情况________

Facing the emergency (紧急情况）,we were at a loss and none of us could____ a solution to the problem.

  A.come about       B.come out      C.come up      D.come up with