rel
abbr. 能量损耗率（rate of energy loss）
例句
You see two parameters: rel and options.
可以看到两个参数：rel和options。
Therefore a rel=canonical would work fine in this situation.
因此一个rel=canonical在这种情景下会更好。
Therefore, the XPath is href:entry/link[@rel='related']/@href.
因此，XPath 为 href:entry/link[@rel='related']/@href。
