This document provides guidance on using the prepositions "in", "on", and "at" in English. It explains that these prepositions are used to talk about time, place, and movement. For time, "in" is used for periods of time like mornings or seasons, "on" is used for specific days or dates, and "at" is used for precise times. For place, "in" refers to enclosed spaces, "on" is used for surfaces, and "at" signifies a precise point. The document encourages memorizing examples to learn the proper uses of these prepositions and provides a table of examples to help distinguish between "in", "on", and "at".