有这么一个故事:一位游客搭乘美国“密西西比号”客轮出游。船在风光旖旎的密西西比河上平稳地航行,一路上的景色美不胜收。游客看到河道情况复杂,有许多浅滩,又听说船长已经在这艘船上工作了几十年,就问他:“船长先生,您在这里航行了这么久,我想您一定对河 There is such a story: a tourist boarding the United States ”Mississippi “ passenger liner travel. The boat sails gracefully across the Mississippi River, beautiful scenery along the way. Visitors to see the river complex, there are many shallows, and heard that the captain has been working on the ship for decades, asked him: ”Captain, you have been here for so long, I think you must be on the river