a duck's webbed feet的用法和样例：
- A duck has a yellow beak and webbed feet.
- Ducks' webbed feet help them to swim.
- Its partially webbed feet help it swim and dive.
- Hesperornis had a sleek, feathered body and long legs with webbed feet.
- Since a beaver spends much of his time in the water, a paddle tail and webbed feet are extremely useful.