碳的循环在学校教科书中已经讲过了。

The carbon cycle is the stuff of school books.

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但是这些是重要的概念，我们已经讲过了。

But these are the important concepts which we've just gone through.

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例如，在《诗篇》，我已经讲过了，我不会再讲。

Look, for example, at Psalm — well, I've already done that I'm not going to do that.

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So, they've lost one of the essential characteristics of these cells that are the same that I talked about earlier.

所以红细胞已经失去了,先前我讲过的,细胞共同属性之一

耶鲁公开课 - 生物医学工程探索课程节选

The other thing that's on this slide here is sort of a simple analogy that I've already described.

这张幻灯片上的其它东西,是一个简单的类比,我已经讲过了

耶鲁公开课 - 生物医学工程探索课程节选

Now, moral feeling is what we'll start off with and we've already discussed this in a different context.

好了，道德情感,是我们首先要讲的一个方面,我们已经讨论过这个问题了,在之前的课堂上。

耶鲁公开课 - 心理学导论课程节选