The following list of prepositions and rules can help you . at 1. Showing a point or location in space or time or on a scale. Examples: We met at a restaurant. I'll see you at nine o'clock. 2. Showing an amount or degree. Example: He drove at a speed of 85 mph. 3. Showing a direction or goal. Examples: He looked at his watch. by Showing nearness, cause, or agent. Examples: He left his briefcase by the door. He was frightened by the loud noise. for 1. Showing how or why something is used, or for whom something is done. Examples: This folder is for recent reports. I have a present for you. 2. Showing how long something happens: He is going to Russia for five days. 3. Showing direction: This is the train for New York. [Note the implied purpose: for = for going to] in 1. Showing inclusion of an object or action in another object, place, activity, occupation, etc. Examples: They took a walk in the city. The computer is in the closet. 2. Showing the general time of an action. Examples: I'll see you in May. They started the company in 1998. 3. Replacing into: showing motion or direction from outside to a point within: Go in the kitchen. Put the ham in the refrigerator. into Showing direction of an object or action so that it becomes included in another object, place, activity, occupation, etc. Examples: He took the plates into the kitchen. He went into the city. I want to get into advertising. of 1. Showing connection, part, or amount: He's the father of Alex. The rear wheels of the car skidded. I would like half a pound of boiled ham. 2. Denoting the object of an action or state expressed by a verb or adjective. Examples: I didn't think of that. I am proud of that. on 1. On top, touching, or being in a position in space or time. Examples: The book is on the table. I'll see you on Monday. 2. On often replaces onto to show movement or position, as in He got on the train 3. On commonly replaces about, as in I am reading an article on thermodynamics. to Movement or action toward something else. Example: He suggested to me that we go inside. with 1. Showing participation, cooperation. Example: I went with him to the theater. 2. Showing the means or instrument. Example: He hit him with a rock. 3. Showing the object of a feeling or behavior. Example: I was angry with him.