“膝”用英语怎么说？

呼气，膝部放松向胸部靠拢。Breathe out and ease your knees in toward your chest.他的一条腿不得不从膝部以上截断。He had to have one leg amputated above the knee.麦卡纳利双膝发软，瘫倒在地板上。Mcanally's knees buckled and he crumpled down onto the floor....

“膝”的拼音为：xī...