So, you might have noticed that we will have spent about 6 and 1/2 lectures just getting to the point where we have only one electron, so we're only up hydrogen so far.

你们可能已经注意到了,我们已经花了６周半的时间,来仅仅是讲到单电子问题的情形，我们现在只研究氢原子。

麻省理工公开课 - 化学原理课程节选

We have only so-called simple meters rather than compound meters.

我们只讨论那些所谓的单拍子,不讨论复拍子

耶鲁公开课 - 聆听音乐课程节选