domestic duck middle covert feather

例句：

1. 1. The domestic duck is a popular bird in many Asian countries.
   家鸭是许多亚洲国家流行的鸟类。
2. 2. The middle covert feathers of the domestic duck are used in traditional Chinese medicine.
   家鸭的中间隐蔽羽毛在传统中医中被使用。
3. 3. The feathers of the domestic duck are soft and fluffy, making them ideal for stuffing.
   家鸭的羽毛柔软蓬松，非常适合填充。