the endless universe, there arenumerous constantly-moving heavenlybodies. The earth on which we live isone of the ordinary planets. It has avery large surface, 71% of which is coveredby water, and the remaining 29% consists ofland and islands. Around the earth there is anatmosphere and inside the earth there is hotmagma. The earth is constantly rotatingrapidly. Its gravitational pull is strong enoughto keep all kinds of objects from driftingaway. This unit introduces some basicknowledge to children so as to arouse theirinterest in exploring the earth.
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