S lowly, Mary walked to class. Mary walked to class and talked with her friends slowly . In this case, did Mary walk slowly to class or talk slowly to her friends. Comparing two items or conditions. Prepositions show relationships of time or space, addition, comparison or contrast, cause or effect, concession, condition, opposition, possession, and source.
Prepositions can be more than one word.
Prepositions are used in prepositional phrases . A prepositional phrase adds more information for the reader about time, place, direction, or manner. During the summer months, they went swimming. If the prepositional phrase only adds information to the sentence and does not limit the meaning of the sentence, commas are used. During the summer months, from June to September, they went swimming.