"For me,I think it was more difficult because I dealt with the guilt of missing my child, having him so far away, then always trying to get home on the weekends to see him, as well as keeping up with school and remaining active,"

VOA: standard.2009.12.04

Well, let's get on with the lesson today.

我们开始今天的课。

麻省理工公开课 - 固态化学导论课程节选