In birds the second finger is the principal strut of the wing, which consists primarily of feathers.

鸟类的第二根手指是翅膀的主要支柱，翅膀主要由羽毛组成。

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In birds the second finger is the principal strut of the wing, which consists primarily of feathers.

鸟类的第二根手指是翅膀的主要支柱，翅膀主要由羽毛组成。

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