Real Scenario(现实场景)
Here's the scenario: you're given the job of checking the pages on a web server for doubled words (such as "this this"), a common problem with documents subject to heavy editing.
任务：检查文本中重复的单词(doubled words)，比如 "this this"。
一些额外的要求：
接受任意数量的文件；
产生报告：包含文件名、行号、单词高亮；
处理跨行的单词；
忽略大小写；
忽略 html 标签，如 <B>very</B> very。
Solving Real Problems(解决现实问题)
Knowing how to wield regular expressions unleashes processing powers you might not even know were available.
学会使用正则表达式可能为你带来前所未有的力量。
