Since the use of Prepositions is one of the most difficult parts of the English language for an ESL student, Ogrinc saw the necessity to create a series of booklets to help better understand the âunusualâ logic in their application in a variety of instances. By going through these pages of exercises, the learner will gradually discover the pattern of usage. It is hoped by the end of the booklet, the use of these common English words will become clearer.