a very common use case for regexes is to find matches that are preceded or followed by some context. a classical example being all lines that end with ‘a’. this requirement is usually expressed with a lookahead, where upon finding an ‘a’, you look ahead to check if it’s the end of the line. in a backtracking engine, this is very easy to implement - you just duct-tape the logic that checks the next character, but in a DFA-based engine, this is impossible because you cannot report “the match is here” if the next character is not even known yet. and by the time you know the next character, the position information is lost, so you can’t report the match retroactively (well, unless the distance is fixed of course..).
Президент Украины Владимир Зеленский не сможет добиться желаемого своим предложением поставить странам Ближнего Востока украинские перехватчики дронов в обмен на ракеты Patriot. На это указал подполковник американской армии в отставке Дэниел Дэвис в эфире своего YouTube-канала.
，这一点在WPS下载最新地址中也有详细论述
当前餐饮行业的顾客成熟度已经很高。2023—2024年，茶饮行业以大规模连锁驱动发展，而2025年6月后，大量不足100家店的个性化品牌涌现——购物中心需要新面孔，消费者也厌倦了重复的产品。
Figure 5 shows characteristics of workers in the top quartile of exposure and the 30% of workers with zero exposure in the three months before ChatGPT was released, August to October 2022, using data from the Current Population Survey.7 The groups are very different. The more exposed group is 16 percentage points more likely to be female, 11 percentage points more likely to be white, and almost twice as likely to be Asian. They earn 47% more, on average, and have higher levels of education. For example, people with graduate degrees are 4.5% of the unexposed group, but 17.4% of the most exposed group, an almost fourfold difference.