Palisades sill

例句：

1. 1. The ship's keel is visible through the water.
   船的龙骨在水面上可见。
2. 2. Thebuilders used a woodenkeel to support theboat.
   建造者使用一根木制基座来支撑船只。
3. 3. Theship's keel was damaged during the storm.
   风暴期间，船的基座受损了。