The circular arc automatic door is reciprocating swing, and its motion parameters are the number of swing per minute, the size of the swing Angle and the travel speed ratio coefficient.

圆弧形自动门是往复摆动，其运动参数是每分钟摆动次数、摆角大小和行程速比系数等。

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Keeping the arm as stiff as a board, swing it in an arc-like motion from the shoulder, making contact in front of the shoulder.

臂要伸直，并保持伸直的姿式不变，以肩为轴把球拍划出弧线，在肩部的前方勾击来球。

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