The central structure of the principalpiece is axoneme.
主段的中心结构是轴丝。
2
The principal chess piece, which can move one square in any direction and must be protected against checkmate.
王象棋中主要的棋子，可以向任何方向移动一个方格，但必须保护它不被将死。
3
The surface roughness in mill machining relates to quiver of work piece, principal axis's eccentricity, cutter abrasion, cutter distortion and other physical or geometry factors.