)The Mississippi River is the most important and largest river in the United States. Nearly all other rivers flow towards it and finally enter it. That.s why Mississippi River is known as the Father of Waters in America. Its water comes from areas which occupies two - thirds of the United States. The Mississippi flows about 6.400 kilometers from its north western source. Before America built railways, The Mississippi River system had been very important for trans-deportation. In the Middle West, Each year, tens of hundreds of ships sailed on the river. In his novel Life on Mississippian Twain gives a very vivid description of the river and the life of the boatmen. In its watercourse Mississippi moves along slowly, appearing harmless. But when the snow begins to melt in spring, there will be more water than the bank can hold. It used to change its course in some places and this led to serious flooding. As sudden changes of its water level could make rocks in the river dangerous. The boatman.s fleeing Mark Twain.s time was full of adventures.
(1). (单选题) What is this passage about?(本题4.0分)
A、 Rivers in the United States.
B、 The Mississippi River.
C、 Mark Twain and his novel.
D、 Boatman life.

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