Unquestionably, the idiomatic usage of english language produces serious difficulties even for very advanced esl students. One particular problem is how to combine prepositions with verbs and adjectives. This app aims to fill the gap by providing an exhaustive list of verbs and prepositions in combinations. But the flashcards, the heart of the app, are completely useless since they do not separate verbs and prepositions, thus forcing you to remember and learn their combinations, but only give the dictionary definitions for their combinations. My suggestion is that you should provide flashcards that show verbs on one side and their combinations on the other.