title: Why does adb return offline after the device string?
body: <p>I use "adb devices" to get following result. Only one device is connected to PC by USB, but we get 8 lines of result. </p>
  
  <p>Could anyone suggest the reason?</p>
  
  <pre><code>WH96TNE00361    offline
  WH96TNE00361    offline
  WH96TNE00361    offline
  WH96TNE00361    offline
  WH96TNE00361    offline
  WH96TNE00361    offline
  WH96TNE00361    offline
  WH96TNE00361    offline
  </code></pre>