dropped bottom

例句：

1. 1. The ship sank to the bottom of the sea.
   船沉到了海底。
2. 2. The foundation of the building is weak.
   这座建筑的基础很薄弱。
3. 3. The boat was driven into the bottom by strong currents.
   大船被强劲的水流冲到了底部。