The antebellum Southern economy became by the 1820s, without any question, a slave economy.

从十九世纪二十年代起至内战前,南方的经济毫无疑问就是奴隶经济

耶鲁公开课 - 美国内战与重建课程节选

But that was over twenty years ago.

但那是二十多年前的事情了。

在洛杉矶写作 - SpeakingMax英语口语达人

Well, he has a wife whom he loves, Penelope, and he has a son whom he has barely seen because he had to go off to Troy almost 20 years ago to fight that battle and he hasn't been home since.

因为他有挚爱的妻子珀涅罗珀,以及一个由于二十年前,他前赴参加特洛伊战争,而几乎素未谋面的儿子

耶鲁公开课 - 古希腊历史简介课程节选

But as the foreign slave trade was closed off, for a whole variety of reasons, only one of which was that there was this passage, sort of a vow, in the original Constitution that the question would be re-visited in 20 years, and 1808 was 20 years.

但随着海外奴隶交易,基于多种原因被封闭之后,这段只提到其中一个原因,是由于最初的宪法契约,这个问题要追溯到二十年前,内战开始前20年即1808年

耶鲁公开课 - 美国内战与重建课程节选