So, this all starts, in terms of putting it in its historical context at the turn of the Century, we said we'd start right in on the 20th Century of where chemistry was.

从历史的观点来看,这些都起源于,上个世纪之交,我们说我们从。

麻省理工公开课 - 化学原理课程节选

For example, in terms of the atomic theory of matter, at the time at the turn of the Century, the understanding was that atoms were the most basic constituent of matter, meaning you couldn't break atoms up into anything smaller - that was it, you're done.

例如在原子理论中,在19，20世纪之交的时候,人们认为原子是,组成物质的最基本粒子,也就是说你不能,把原子再分割了,就这样了。

麻省理工公开课 - 化学原理课程节选