47.
According to the
advertisement, a six yuan ticket is for .
A.Russian Concert B.Korean Songs
C.South Korean
Films D.Leon’s Show
D
A
serious threat to farmers in many parts of the world is erosion. Erosion occurs
if a large area of land is cleared of trees and is then badly treated by the
farmers. The rain and winds may gradually wash away, or blow away, much of the
topsoil. When this happens, crops of wheat or corn become weaker and weaker
until nothing grows well. If erosion continues, it will turn good land into a
desert.
In the
past, when erosion appeared, farmers sometimes moved to a new place to farm.
Sometimes they could not move, but continued to try to grow food in the
unhealthy soil. This caused them to sink into poverty. Soon some people
realized that there was little rich, fertile soil in the world, government
began to try to stop erosion.
One of
the first experiments to stop erosion began in the United States in 1933. The
experiment was carried out in the area of the Tennessee
River. Floods and had farming in this area had ruined(毁坏)land that had
once been rich. As a result, most of the people living around the Tennessee River were very poor.
The
government built big dams across the river and stored the water for use during
the dry season when there was no rain. The government workers also helped
farmers to fertilize their soil and to learn new farming methods which could
stop erosion.
At the
beginning, the farmers were not interested. But soon, good healthy crops began
to appear on the land where new methods where used. Ten years after the
extremely prosperous, the great success of this experiment had led similar
projects in the other parts of the world.