Critics say the national exam is biased, since it presumes a level of knowledge and cultural background that students from working class families may not have.

VOA: standard.2010.02.02

Let me give a little bit background on positive psychology: how we came about and how this class came about.

下面介绍一下积极心理学的背景：,它是如何诞生的，这门课是如何诞生的。

哈佛公开课 - 幸福课课程节选