A doctor quickly cut off his left arm and stopped the heavy bleeding.

VOA: special.2009.10.15

And it turns out that when it was quiet, the arm was moving to the left.

事实上，当寂静的时候，手臂在向左移动。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选

This is happening while making arm movement from the left into the right.

当手臂从左向右活动的时候，就会出现这样的情况。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选