名词
中文翻译：Unknown
同义词：
['annular', 'ring-shaped']
例句：
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1. The moon is a perfect example of an annular object.
月亮是完美的例子，一个环形物体。
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2. The planets are all annular in shape.
行星都是圆形的。
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3. The ring-shaped structure was formed by the collision of two planets.
环形结构是由两个行星的碰撞形成的。