發送短信 : Complexity issues in synchronisation

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