Even there, a horse is not really a rigid body, unless it's been dead for a long time.

马甚至都不是真正的刚体,除非是死了很长时间了

耶鲁公开课 - 基础物理课程节选

There are problem in that a horse must be treated when we study rigid bodies.

当我们学习刚体的时候,把马看做什么就是个问题了

耶鲁公开课 - 基础物理课程节选

That comes later when we study what we call "Rigid bodies".

以后当我们会学到刚体时会讲到

耶鲁公开课 - 基础物理课程节选