Your feet should be flat on the floor or supported by a footrest.

你的脚应该平放在地板上或用一个脚凳支持。

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This means your neck and spine should be in a neutral position, shoulders and torso relaxed, knees bent at 90 degrees with both feet flat on the floor.

这也就是说你的脖子和脊柱应该处于中正的位置，肩膀和躯干放松，膝盖弯曲呈90度角，双脚平放在地面上。

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