计算出的值的XPath只能是叶节点。

The XPath for a computed value should be a leaf node only.

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例如，一个叶节点知道它自身及其父节点。

For example, a leaf node knows itself and its parent.

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最佳实践：在组织层次结构的叶节点创建商店。

Best practice: Create stores at leaf nodes in the organizational hierarchy.

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So, that's going to be important later when we get to bonding, but just take note of it now, we have two nodes, or we have two lobes, excuse me, each with a separate phase.

这等到我们之后讲到成键时是非常重要的，现在先要记住，我们有两个节点，不好意思，是两个叶瓣，每个都是不同的相位。

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