The Contract is written in quadruplicate (two for original and copy respectively) which shall become valid on the date of signature.

本合同一式四份(正副本各两份)自签署后生效。

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Any additions, changes and modifications should be carried out in writing to this contract, authorized representatives of both parties effect the date of signature.

本合同的任何补充、变更和修改应当以书面方式进行，于双方授权代表共同签字之日起生效。

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This contract shall come into force for thirteen (13) months from the date of signature of the contract by parties and extended if no party opposite when the contract expire.

本合同自买卖双方签署之日起生效，有效期为13个月并可以自动延长- - -若双方在合同期满时无异议的话。

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They want a piece of paper, generated at a specific time and place, preferably with a date and signature on it.

FORBES: The Web Is A Thing Out Of Time