adv.递归地
If you have a correct definition of you cubeNode it is very easy to create an octree recursively. 如果你正确的定义了你的立方体节点，那么递归地创建一个八叉树是很容易的。
Location paths can recursively contain expressions that are used to filter sets of nodes. 定位路径可以递归地包含用于过滤节点或集合的表达式。
