Quadtrees
四元树
🗣️ 情景例句
If you have time around Christmas, please come to visit my family.
如果你圣诞节前后有空，欢迎到我家来玩。
By other's faults, wise men correct their own.
他山之石，可以攻玉。
Refuse politely any cold drink from an unknown source.
应谢绝任何不明来源的冷饮。