As an alternative to value comparisons, you can use the self axis (denoted by a dot ". ") to express a "between" predicate.

除了值比较，还可以使用self轴(由点“。”表示)来表达“between”谓词。

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The locator attribute supports the child axis (/), descendant-and-self-axis (//), and attribute axis (@).

locator 属性支持子轴（/）、后代及本身轴（//）和属性轴（@）。

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Results: Comparing with the self control group, the length of axis, cornea diameter and fundus were normal.

结果：实验组与自身对照组比较，眼轴长度、角膜直径、眼底形态均无差异。

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Over the past five years the Russians developed a prototype of a vertical axis wind turbine with an innovative airfoil that enables the turbine to self-start.

FORBES: Magazine Article