The peple on earth belong to many different countries.We speak many different language and have different ideas.But we are all people born on earth .All of us live and die on this planet.We have never known any other home.
Men believed for thousands of years that the earth was the center of e_____.They believed the sun and the stars circled around us .
The old ideas of men should not s______us.Most fo us only believe what we see.Many years p______,and then people know that our earth is only a very small part of a great universe,and earth is going around the sun.
What do we know about the place of our earth in space?We know thatthe earth is one of eight planets m______around the sun. We call the f_____of the sun and its planets the solar system.
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