發送短信 : Synchronization in cooperative communication

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|  __ \\   /_   _//  | \| ||   / _ \\    / ___// 
| |  \ ||   -| ||-   |  ' ||  / //\ \\   \___ \\ 
| |__/ ||   _| ||_   | .  || |  ___  ||  /    // 
|_____//   /_____//  |_|\_|| |_||  |_|| /____//  
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