You use this pattern whenever you want to express that you have experienced something in the past previously.

每当你想表达你之前已经经历过某事的时候，你就可以用这个句型。

I've already 课堂 - SpeakingMax英语口语达人

And as pointed out in your reading, the characters all seem to deal with something about the past.

中都有所体现，在你的阅读材料中也提到了,戏中角色似乎都在处理关于过去的一些问题。

麻省理工公开课 - 电影哲学课程节选

And Jenner, because he was a trained physician, because he knew something about the scientific method, did something that these more ancient healers had not done in the past, was that he wrote down what he did.

而詹纳,因为他是个受过训练的医生,懂得一些科学方法,他做了那些古老的医生们没有做的事,就是记录了自己的所作所为

耶鲁公开课 - 生物医学工程探索课程节选

and something that you were doing or how you were being in the past.

和一些你过去已做过的事情，或是你过去是什么样子的。

I was 课堂 - SpeakingMax英语口语达人

And something that's happened in the past that's continuing to happen.

或者在过去发生的某事，现在仍在继续。

I've been 课堂 - SpeakingMax英语口语达人

And archaeology supports this picture of merging of peoples, a picture of the merging of peoples, rather than conquest or even large-scale immigration, because the new settlements in this period show such continuity with the past, not a complete break, not the initiation of something radically new.

考古学肯定了民族的融合，多个民族相融合的图景，而不是征服或者是大规模的移民，因为这一时期新的定居表明,与过去的连续继承，而不是完全的断裂，不是完全的新的开始。

耶鲁公开课 - 旧约导论课程节选

Something that was far gone in the past.

这些事都发生在遥远的过去，

I was 课堂 - SpeakingMax英语口语达人

Or something you were doing in the past.

以及你过去做过的一些事情。

I was 课堂 - SpeakingMax英语口语达人

I'm sure some of you have dealt with electrophoresis gels in the past and it's really just a slab of something like Jell-O where you can put a sample at one end of the Jell-O, your sample of fragmented DNA.

我相信在座肯定有些已经接触过电泳凝胶,真的挺像一块板状果冻的,你可以把一段样本放在"果冻"的一端,你的DNA片段样本

耶鲁公开课 - 生物医学工程探索课程节选