圆括号用作分组操作符。

Parentheses are used as a grouping operator.

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然而，那篇文章没有解决在聚集中支持分组操作符的问题。

However, it specifically did not address the issue of supporting grouping operators for the aggregates.

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以上表达式综合运用了字符分组，贪婪操作符、回溯，以及最小化组团来匹配嵌套标签。

The above expression combines character groups, greedy operators, back-tracking, and atomic groups to match nested tags.

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