This document discusses the uses of the prepositions "in", "at", and "on" as they relate to place and time. It provides examples of how each preposition is used to indicate location, such as "in" for countries or closed spaces, "at" for exact addresses or public places, and "on" for things above a surface. It also examines their uses relating to time, with "in" used for months, years, centuries, and parts of the day (except night), "at" used for hours and precise times, and "on" used for days of the week and dates. Overall, the document serves as a reference for the different ways these common prepositions of place and time are