"The brain-machine interface is a system that allows disabled people, people suffering from physical disabilities to communicate with external world and also to control devices."

VOA: special.2011.04.04

I mean maybe up the street we whisper, but here we know it. And, so here is a different kind of system where we have a constant external pressure.

或许在街上你们低声细语，但在这里不应该这样，这是另一个系统,我们有一个恒定的外压强。

麻省理工公开课 - 热力学与动力学课程节选

The respiratory system, for example, the renal system, the digestive system, these are examples - three examples of organ systems that contact the external environment.

例如,呼吸系统,泌尿系统,消化系统,这些系统,这三个系统,与外环境相联系

耶鲁公开课 - 生物医学工程探索课程节选

It's the pressure the external world is applying on this poor system here.

V是气体初态和,末态的体积之差。

麻省理工公开课 - 热力学与动力学课程节选

We've talked about the interesting way in which the digestive system contacts the external environment.

我们会讲到,消化系统与外环境之间十分有趣的联系

耶鲁公开课 - 生物医学工程探索课程节选