Subtyping
v. 子类型化（subtype的现在分词）
🗣️ 情景例句
Three scoops?
三杓？
Be considerate toward the poor.
应常为穷人着想。
Tomorrow is christmas Eve, and my father and I went to choose a Christmas tree today.
明天是圣诞节前夜，今天我和父亲去选圣诞树。