With ActiveRecord, you can also nest the: include option, but only one level deep.

通过ActiveRecord，还可以嵌套：include选项，但嵌套深度只有一级。

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But, our experience shows that nesting the two languages more than one level deep is usually not needed to express the desired query logic.

但是，我们的经验显示，表达所需的查询逻辑通常并不需要两种语言的嵌套层次超过一层。

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The hierarchy of menus has been flattened down until it is only one level deep .

这里菜单只有一级，层次关系扁平化了。

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