None. When you walk through that door it's an act of free will, and I will not have anything other than complete silence.

走过那道门,是你的自由，我不会做其他事,除非保持安静。

麻省理工公开课 - 固态化学导论课程节选

None. When you walk through that door it's an act of free will, and I will not have anything other than complete silence.

走过那道门,是你的自由，我不会做其他事,除非保持安静。

麻省理工公开课 - 固态化学导论课程节选