This document provides examples of the use of prepositions "in", "on", and "at" to indicate location, time, and other relationships. It explains that "at" is generally used for precise times and points, "in" is used for enclosed spaces, months/years, and periods of time, and "on" is used for surfaces and days/dates. Some examples given include being "at the door", "in the garden", and "on the wall" for location and "at 3 o'clock", "in May", and "on Sunday" for time. The document also gives guidance on using these prepositions to express activities, states, devices, body parts, and other relationships.