Later,Alfred Wegener said the continents had once been part of a huge area of land he called Pangaea.

VOA: special.2010.01.12

The next year 403 the Tyrants The Thirty as they were called were driven out and a democratic government was once again reestablished in Athens.

来年，即公元前403年，暴君,别名三十,就被罢黜,民主政府再次重立于雅典。

耶鲁公开课 - 政治哲学导论课程节选

Once you can take one derivative, you can take any number of derivatives and the derivative of the velocity is called the acceleration, and we write it as the second derivative of position.

只要你能求一阶导数,你就能求任意阶的导数,速度的导数被称为"加速度",我们把它写成位移的二阶导数

耶鲁公开课 - 基础物理课程节选

Science on Tap meets once a month at a bar called the Schlafly Bottleworks.

VOA: special.2010.05.14

So, the Commune begins on the 18th of March, 1871, and it lasts until the end of May, 1871. Lenin once called it the "Festival of the Oppressed"; and Lenin was wrong about many things, he was right about a few things but wrong about many, but he got that one right.

由此,巴黎公社在一八七一年三月十八日成立,并于同年的五月底被政府所瓦解,列宁将这段时间称为"受压迫者的庆典",列宁做错过不少事情,他做对的事情寥寥无几,但对于巴黎公社的评价是正确的

耶鲁公开课 - 1871年后的法国课程节选

Once the water is heated, it is kept hot with material called insulation.

VOA: special.2009.04.20

Well in C and other languages that we'll see this semester, you use what's called the for loop, and this as syntax isn't quite as straightforward but once you know what to look for, it's very easy to understand.

在C语言和一些我们这学期将要接触的编程语言中，你将会用到所谓的for循环，也许作为一种语法规则，它看起来不是那么的通俗易懂,但是你一旦知道曲中奥妙，就不难理解了。

哈佛公开课 - 计算机科学课程节选

The New York Times once called him "America's philosopher."

VOA: special.2010.01.07

He referred to criticisms once directed at the pop star for what some had called erratic behavior.

VOA: standard.2009.07.07

St.Louis has two science cafs. The second one - sponsored by Washington University - meets once a month during the academic year at a bar called the Schlafly Bottleworks.

VOA: standard.2010.05.04