They have a material that supplies electrons and a power source that lifts the energy level of those electrons.

VOA: special.2010.09.01

Okay, so when you are working with source material that looks like this, there is in fact no such thing as infinite zoom in computer science.

当我们处理,这样的原数据时，事实上计算机科学中,并不存在无限放大。

哈佛公开课 - 计算机科学课程节选

And source critics looking at this material discern numerous, diverse sources that are interwoven throughout.

一些材料批评学家认为这个故事，是由很多素材交织在一起的而成的。

耶鲁公开课 - 旧约导论课程节选

There is in Frost no God, no transcendental source of guidance or consolation, nothing out there in the world but the material conditions of our circumstances.

在弗罗斯特的诗里，没有上帝，没有卓越的指引和安慰，这个世界里什么都没有,除了我们生活环境的物质条件。

耶鲁公开课 - 现代诗歌课程节选