Ontology can be viewed as a tree structure. Concepts comprise of class and subclass, the relationships between which are tree's edges.

一个本体可以抽象为一个树状结构，概念由类与子类构成，类与子类之间的关系是树中的边。

youdao

Also any data change on a subclass involves two tables: the super class table and the subclass table.

任何子类数据的修改都涉及两张表：超类的表和子类的表。

youdao

Instead of creating a new window and setting it up, you put the Gtk.Window class into a subclass and move all setup code into a constructor.

现在不再创建并设置新窗口，而是把Gtk . window类放进一个子类，并把所有设置代码移动到构造函数。

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