三、书面表达。
地球是我们赖以生存的家园，只有了解它，才能更好地爱护它。请你根据下列提示和本单元的内容，以“Earth”为题用英语写一篇短文，向同学们介绍地球的相关知识。
内容包括：
1. 46 billions years old.
2. It is one of the eight planets of the solar system.
3. A diameter of 13,000 kilometers.
4. Oceans cover about 71% of Earth.
5. ...
写作要求：
1. 文中须包含以上要点提示，可适当发挥；
2. 文中不得出现本人的真实姓名或校名；
3. 词数70个左右（开头和结尾已给出，不计入总词数）。
Earth
Earth is our home planet. ____________________
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Earth is our home. We must love it and protect it.