圆天是一个汉语词语，读音是yuán tiān，是指古人认为天呈圆形。故称圆天。
在那一天，月亮是圆的，所以家人都想聚在一起吃月饼。
On that day, the moon is round. So families want to get together and eat mooncakes.
一天晚上，月亮又圆又亮，他在月亮上发现了嫦娥。
One night, when the moon was round and bright, he found Chang'e was on the moon.
有一天，圆终于找到了很适合它的那块。
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