folding fin rocket

例句：

1. 1. The airplane's folding fin is designed to reduce the weight and increase efficiency.
   飞机的折叠翼设计是为了减少重量和提高效率。
2. 2. The fish uses its folding fin to glide through the water.
   鱼使用它的折叠鳍在水中滑行。
3. 3.The bird's folding fin allows it to fly at high altitudes without flapping its wings.
   鸟的折叠翼允许它在高空飞行而无需拍打翅膀。