Obsidian is a kind of black glass formed when the heat of a volcano melts the silica material in sand.

VOA: special.2009.09.16

There is a kind of drum beat of thematic material as these scenes pile up.

剧情在不断变换,的场景下不断上演。

耶鲁公开课 - 1945年后的美国小说课程节选

So part of the goal here is, this should not be a grueling, exhausting kind of task, it's really something that should be helping you learn the material.

所以部分目标在于，这不应该是一个累赘，不是那种沉重的任务，它应该能帮助你,学习材料。

麻省理工公开课 - 计算机科学及编程导论课程节选

Well really, the things we've looked at thus far can you do after just a semester of this kind of material and exposure to this particular world.

当结束这样一门课时,你是不是能通过学习和接触计算机科学,也做出我们刚刚看到的这些东西。

哈佛公开课 - 计算机科学课程节选

Spirit is merely a kind of bodily form of energy, and God at the beginning of time infused this energy into the entirety of the material world at the Creation.

灵魂不过是能量的一种物质形式，上帝在时间之始创世纪之际将这能量,注入到了整个物质世界之中。

耶鲁公开课 - 弥尔顿课程节选

A person is just a certain kind of material object.

人只不过是一种物质实体

耶鲁公开课 - 死亡课程节选