Then, after you define what your system is, whatever is left over of the universe is the surroundings.

当你定义了你的系统后，宇宙的其余部分,就是环境。

麻省理工公开课 - 热力学与动力学课程节选

There's no heat flowing from the environment to the system. I have to define my terms.

系统与外界间,并没有热传递发生。

麻省理工公开课 - 热力学与动力学课程节选

It depends on what you define, exactly what you define in your system.

它取决于你的定义，尤其是在你系统中的定义。

麻省理工公开课 - 热力学与动力学课程节选