These acquisitions fit right into the business model even though it takes some explaining.Language-learning app Duolingo (DUOL -1.86%) had nearly 100 million monthly active users as of the first quarter of 2024. And as a person with a background in linguistics, I believe this statistic is more impressive than most people realize.Anecdotally, I've found it incredibly difficult to keep language learners motivated. Think about it: Almost everyone can express themselves well in their primary language and someho ...