求翻译：　　四肢着地，膝盖并拢，双掌与肩同宽，大腿、手臂与地面垂直。抬起左膝，同时提胯，并且向后伸展右腿，右脚脚背弯曲。伸右腿时，臀肌收缩，并将腿稍稍向外送。胯部保持平衡，身体重心放在双掌和左脚上。是什么意思？

　　Limbs, knees together, double Palm and shoulder width, thighs, arms perpendicular to the ground. Lift the left knee, and hip, and stretch the right leg backward, right instep of the foot is bent. When you stretch the right leg, gluteus contraction, and sending leg slightly outward. Crotch to maintain balance, and body weight in two-hand and left foot.