So, let's go back to the thrilling days of the end of the 19th century, and just take stock.

让我们回到激动人心的,19世纪末，稍微想一下。

麻省理工公开课 - 固态化学导论课程节选

What did we know at the end of the 19th century about the structure of the atom?

在19世纪末,关于原子结构我们了解多少呢？

麻省理工公开课 - 固态化学导论课程节选

This went out at the end of the 19th century, and so on.

这在19世纪末期后就结束了。

麻省理工公开课 - 固态化学导论课程节选