But the acquisition of radioactive material for a so-called 'dirty bomb,' which is radioactive material that is dispersed with a conventional explosive device, that is not that challenging.

VOA: standard.2009.05.01

Something that's not a material object.

一个不是由物质实体构成的东西

耶鲁公开课 - 死亡课程节选

So that would probably be de Broglie's answer for why, in fact, we're not observing the wavelength behavior of material on a day-to-day life.

所以那就可能是德布罗意关于,为什么我们无法再日常生活中,观测到物质的波动行为的答案。

麻省理工公开课 - 化学原理课程节选

Point I want to make about this, though, is that we are going to cover a lot of material that is not in the assigned readings, and we do have assigned readings associated with each one of these lectures.

要说的一点是,我们会有很多,不在拓展阅读里面的材料，而且还有涉及到,每节课内容的拓展阅读。

麻省理工公开课 - 计算机科学及编程导论课程节选

So, there's a tremendous variety of material in this library, and it follows from the fact that it's not a book but an anthology of diverse works, that it's not an ideological monolith.

在这座图书馆里有丰富多样的材料，因此这不仅是一本书,而是各种各样文献的合集，这不是什么讲思想道德的长篇大论。

耶鲁公开课 - 旧约导论课程节选

So they have to be engineered to be inert so that they can be safely inside a system and there's not every material you could pick would have that property.

缝合线必须是惰性的,以便确保植入人体后的安全性,不是随便哪个材料都能做到这一点

耶鲁公开课 - 生物医学工程探索课程节选

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

For example, one thing that could happen is that you build it up with wood and clay, you pick the wrong material for a bridge, and it will not stand up to the forces of nature.

例如,其中的一个问题是,选择了木头和粘土作为造桥的材料,你就选错了材料,这座桥难以与自然力相抗衡

耶鲁公开课 - 生物医学工程探索课程节选