outer buoy

例句：

1. 1. The outer buoy was damaged during the storm.
   暴风雨中，外浮标受损。
2. 2.The outer buoy was used to mark the boundary of the lake.
   外浮标用于标记湖泊的边界。
3. 3. The outer buoy was raised to prevent ships from entering the restricted area.
   将外浮标升起以防止船只进入限制区域。