1. Some time ago the United States Navy, for instance, examined a very large number of men working on aircraft carriers:
    例如，美国海军前些时候调查了许多在航空母航上工作的人，

2. Seventy-two search planes, plus dozens of ships, failed to turn up any sign of the missing aircraft.
    72架搜索飞机加上几十艘船，都没能找到失踪飞机的任何踪影。

3. Suddenly we heard the commander say "enemy" aircraft had been sighted.
    突然，我们听到指挥官说发现"敌"机。

4. Ice formed on the extremities of the aircraft wings.
    机翼末梢结起了冰。