To withstand the force of the oncoming air, a flight feather is shaped asymmetrically, the leading edge thin and stiff, the trailing edge long and flexible. To generate lift, a bird has merely to ...
Kiat adds: "It's really surprising, that with so many styles of flight we can find in modern birds, they all share this trait of having between nine and eleven primary feathers. And I was ...
当前正在显示可能无法访问的结果。
隐藏无法访问的结果