E nwere ụdị atọ nke elu-nrụgide flange akara ihu: ewepụghị akara ihu, adabara ala nrụgide, na-abụghị egbu egbu oge oge; Concave na convex akara n'elu, kwesịrị ekwesị maka obere oge nrụgide dị elu; Tenon na groove akara elu, dabara maka ire ọkụ, mgbawa, mgbasa ozi na-egbu egbu ...
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