The reason why I do put them up is so that you have the opportunity if you want to see it again or if you have to miss a class.

我之所以把资料放在网上是为了,让你们可以重温或者学习错过的课程。

哈佛公开课 - 幸福课课程节选

because I see the problem with our society right now, is that people don't have the opportunity to sustain themselves

因为我们现在的问题是人们没有机会来供养自己，

要学习环境法 - SpeakingMax英语口语达人