Although all birds have feathers and all birds have wings, some birds do not fly  For example, penguins and ostriches use their wings to move in a different way from other birds  Penguins use their wings only to swim under water at high speeds
Ostriches use their wings only to run with the wind by lifting them as if they were sails
Some chairs are used only as decorations, and other chairs are used only to tame lions. Ttherefore, not all chairs are used for sitting in despite the fact that all chairs have a seat and some support such as legs.