PREPOSITION A preposition is a word used to link nouns , pronouns , or phrases to other words within a sentence. They act to connect the people, objects, time and locations of a sentence. Prepositions are usually short words, and they are normally placed directly in front of nouns. EXAMPLES I prefer to read in the library. He climbed up the ladder to get onto the roof. Please sign your name on the dotted line after you read the contract. Go down the stairs and through the door. He swam across the pool. Take your brother with you. Prepositions of Time Basic examples of time prepositions include: at, on, in, before and after . They are used to help indicate when something happened, happens or will happen. It can get a little confusing though, as many different prepositions can be used. Prepositions of time examples in the ...