A comet is a huge ball of frozen gas and dust that often releases a long trail of material as it nears the sun.

VOA: special.2009.09.30

We have come a long way from the gas discharge tube to the heavens.

我们在从气体放电管到,世界还有很长的路要走。

麻省理工公开课 - 固态化学导论课程节选