题目内容：
根据以下资料，回答题：Directions: The following is a passage about contract. After reading it, you are required to complete the outline below it ( No. 46 to No. 50．. You should write your answers briefly ( in no more than three words． on the Answer Sheet correspondingly.
A contract is an agreement between two or more people in which one person agrees to do something by a specified date in return for something done by the other. Usually the contract is a written document signed and dated by both parties. It must state clearly the consideration, that is, what is to be given or done by one person in exchange for what is given or done by the other. If one person does what was promised and the other does not, the other may be sued in court and required by court order to make good. He or she may also be required to pay for damages suffered as a result of the failure to perform. The things to be done by both parties must be stat- ed in definite terms or the court will hold that contract is too vague and general to be enforced. Similarly, the time period within which the work is to be done must be definite or the court will say that the document is not a contract.
A contract is an 46______________
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