that tell about life in America during two different periods.

VOA: special.2009.03.23

When these tyrannies take place, they last for different periods of time, but when the tyrant is removed, what follows after that is, there is never again in that town a one-man rule of any kind.

当僭主统治步入历史舞台,它走过了很多历史时期,但当它寿终正寝之后,在那座城邦里再也没有出现过,任何形式的独裁者了

耶鲁公开课 - 古希腊历史简介课程节选

They thrust together different texts, different languages, writing from different historical periods, all there, compressed in that remarkable mad song that concludes the poem.

它们将不同文字，不同语言，不同历史时代的书写，相互交织穿插，都呈现在那里，摘要叙述在一首举世闻名却又疯狂的结尾歌里。

耶鲁公开课 - 现代诗歌课程节选

They represent different periods of Chinese-American history.

VOA: special.2010.03.03

The trouble with the etymology of theory and the way in which the word has been used traditionally is that sometimes it actually means practice, and then at other historical periods it means something very different from practice, something typically from which practice is derived.

理论这个词在词源,和传统的使用方法上的复杂之处在于,它有时候指的是实践，但在特定的历史时期,它指的是和实践非常不同的东西，也就是实践产生的依据。

耶鲁公开课 - 文学理论导论课程节选

So now there is a problem of credibility of what the government is going to do, and of course the situation is different to situations in other periods because now there is a common currency."

VOA: standard.2010.06.24