Definition: a large, round object in space that moves around the sun or another star Level: B1
地球是离太阳第三近的行星。
Earth is the third ___planet from the sun.
其他星球上可能存在智慧生命吗？
Could there be intelligent life on other ___planets?
我正在写一篇关于火星的报告。
I'm writing a report about the ___planet Mars.
