活跃的聚会的英文：
knees-up

slide off the knee
从膝盖上滑落下来

He has a pain in the knee.
他膝盖酸痛。

The knee is in pristine condition.
膝盖已经恢复到正常的状态。

She grazed her knee.
她擦伤了膝盖。

knee joint flexion and extension exerciser
膝关节弯曲伸长训练器