You have closed end funds, trade as a security listed on the stock exchange, but what they do is own other securities.

假如你持有封闭式基金，这种基金在证券交易所作为一种债券进行交易，但是实际上它们做的是持有其他债券。

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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