科学家表示，如果不采取措施减少密西西比河的含氮量，未来几年死水区会愈发扩大。

And scientists say it will grow larger in years to come, if something is not done to reduce the amount of nitrogen in the Mississippi River.

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And you will find, as we will in the next few weeks, the Southern political power by the 1850s and 1860s is really no longer in Virginia, or even South Carolina, it's out in the Mississippi Valley.

在接下来的几周课中你们会发现,截至十九世纪五六十年代,弗吉尼亚,南卡罗来纳州和密西西比河谷,已经不存在南方政权力量了

耶鲁公开课 - 美国内战与重建课程节选