down-feather的用法和樣例：
例句
- In a plumulaceous feather, barb ridges grow straight without any helical movement.
在絨羽上，羽枝脊則直直生長，不做螺旋形移動。 - Common allergens include pollen, animal dander, down feathers, mites, chemicals, and a variety of foods.
常見的過敏原包括花粉，動物皮屑，絨羽，蟎類，化學品，以及各種食品。
辭彙搭配
- knock someone down with a feather 使某人十分驚奇...
