Second thing, we started talking about the periodic table and I believe that it's a hallmark of any educated person in the 21st century who is technically literate to know the periodic table by heart.

第二点，我们之前讨论过元素周期表,我相信这是个标志性的特征,对于那些在21世纪里,用心去学习,元素周期表的人来说。

麻省理工公开课 - 固态化学导论课程节选

Wooly Willy It turns out these are really hard to find in the 21st century.

，Wooly，Willy？,在21世纪很难发现这些东西了。

哈佛公开课 - 计算机科学课程节选

But the question is how are those of us of this generation, living that ethic out in the early 21st century?

但问题是,我们这代人如何，将在21世纪初的生活中体现这一道德？

普林斯顿公开课 - 人性课程节选

That is a remarkable endeavor and one that I think in the early 21st century which is too much defined by religious conflict should very much be held up and lived out.

这是巨大的努力,我认为这种努力也是,过多得被宗教冲突定义的21世纪初期,应该坚持并实现的努力。

普林斯顿公开课 - 人性课程节选

And we can argue about whether or not that's work, but that has been the intention certainly in the 20th century and now 21st.

我们可以对这种现象有所争论，但这个观点,肯定是20世纪和现在21世纪的焦点。

普林斯顿公开课 - 人性课程节选