firing line
noun
1- the front line of troops in a battle（战斗中部队的）射击线。
1.1
the firing line
a position where one is subject to criticism or blame because of one's responsibilities or position挨批评（或受责备）的地位：the referee in the firing line is an experienced official.
成为众矢之的的那位裁判是一位经验丰富的官员。