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Did you ever hear the saying, “it’s easier to get the Mississippi to change its course than get a stubborn child to change his mind”? I guess whoever made this one up didn’t know that the Mississippi actually does change its course about every thousand years or so.
你是否听说过这句谚语：“让密西西比河改道比让固执的小孩改主意更容易。”我猜编出这句谚语的人不知道密西西比河的确每隔一千年左右就会改一次道。

How could a river change its course? Actually, the whole process is due to silt¹. Every year, erosion from farm fields and building projects washes millions of tons of soil into streams and rivers. When these tributary² streams and rivers empty into the Mississippi, the floating soil particles are carried along in the fast-moving water from the heart of the continent towards the delta³, where the river meets the sea.
河流怎么会改道呢？实际上，改道的全过程都是淤泥在起作用。每年，农田和建筑工程由于侵蚀作用而将大量泥土冲入溪流和河水之中。当这些支流的小溪和河流注 入密西西比河时，漂浮在其上的土壤颗粒也随着快速流动的河水顺流而下，从大陆中心流向三角洲地区——也就是河流汇入大海的地方。

At the delta, the main channel of the river forks into many smaller channels. The water in the main channel slows down, and the floating soil settles to the bottom. Over time, this sediment⁴ builds up, and the main channel becomes shallower and shallower until it finally overflows⁵ and forms a new river, leaving the old channel to become a swamp.
在三角洲地区，密西西比河的主河道分叉，分出许多小河道。主河道的河水流速变缓，悬浮的土壤颗粒沉入河底。久而久之，这些沉积物将河底抬高，主河道变得越来越浅，最终导致河水漫过河道形成一条新的河流，而旧河道则成为沼泽。

Over the past eight thousand years, the Mississippi’s main channel has become clogged⁶ up and changed course at least seven times. Under natural conditions the city of New Orleans should now be underwater, but this has been prevented by the Army Corps⁷ of Engineering’s spending millions of dollars to prevent the Mississippi from changing course.
在过去的八千年里，密西西比河的主河道至少阻塞并改道了七次。在自然状态下，现在的新奥尔良市应该已经身居河底了，但是美国陆军工程花费了上百万美元阻止了密西西比河再次改道。

So maybe the saying is wrong. Maybe stopping the Mississippi from changing its course is the really hard thing to do.
所以，也许谚语是错误的。阻止密西西比河改道才是件困难的事情。