There are multiple mechanisms that a cell can use to decide which genes it is expressing at any one time and which ones are not expressed.

在某一时刻,决定细胞中哪些基因表达,哪些基因不表达的机理十分复杂

耶鲁公开课 - 生物医学工程探索课程节选

It has to be complex, because we're asking the immune system to be able to respond to every potential foreign pathogen that we come into contact with.

免疫系统是十分复杂的,因为我们需要免疫系统,能够对我们身体接触到的,任何潜在的外来病原体进行反应

耶鲁公开课 - 生物医学工程探索课程节选

And then, they have this very complicated back-and-forth about things that they remembered, or didn't, and they hashed these things over: Then Carlo asked Dean if he was honest and specifically if he was being honest with him in the bottom of his soul.

于是，他们有了这个十分复杂的,关于他们想得起来想不起来的事的来回选择，并且他们充分讨论了这些事情：,然后卡洛问迪恩他是否诚实，特别是他是否,从灵魂深处对他诚实。

耶鲁公开课 - 1945年后的美国小说课程节选

That's a really complicated question that we have gotten very confused about.

这也依然是一个复杂的问题,人们现在对此十分困惑

耶鲁公开课 - 生物医学工程探索课程节选

You might not want to know all of it and that's a really complicated question for an individual to figure out and a complicated question for society to figure out, what you want to make of available in the regard.

你不想什么都知道,这是个十分复杂的问题,无论是对个人,还是对社会都是如此,我们应该怎样控制它的使用范围

耶鲁公开课 - 生物医学工程探索课程节选