Prepositions are one of the most persistent grammar challenges for adult ESL/EFL learners—especially in real-world writing where accuracy matters. This resource provides 100 targeted error-correction sentences across 10 key preposition rules, helping learners master everything from in/on/at to complex collocations and fixed expressions. Each sentence is written in authentic adult contexts—including business communication, travel, academic writing, and workplace situations—so learners practi