Submitted by e-mail by 5 p.m.

东部标准时间下午五点前通过电子邮件提交。

麻省理工公开课 - 固态化学导论课程节选

Final question Tom, and this is from a viewer who send in the question by Twitter,to be submitted to you.

最后一个问题，这是一个观众的提问,通过twitter网站，提交给你。

斯坦福公开课 - 经济学课程节选