This document discusses prepositions and provides examples of their use. It begins by defining a preposition as a word that indicates the relationship between a substantive and a verb, adjective, or other substantive. Examples are then given of common prepositions like in, on, and at. Specific uses of on and at are outlined, such as using "on" for surfaces you can lay something on and "at" to indicate a point in time or place. The document concludes by encouraging the reader to practice prepositions through exercises.