flat keel

例句：

1. 1. Theflat keel makes the boat stableand easy to steer.
   平底船首使船稳定且易于操控。
2. 2. The flatkeel is a common feature onfishing boats.
   平底船首是渔船的常见特征。
3. 3. The flat keelhelps reduce drag during sailing.
   平底船首有助于减少航行时的阻力。