發送短信

數:

提供者:

CAPTCHA:

  _____     _____     _____    _    _             
 / ____||  |  ___||  /  ___|| | || | ||     ___   
/ //---`'  | ||__   | // __   | || | ||    /   || 
\ \\___    | ||__   | \\_\ || | \\_/ ||   | [] || 
 \_____||  |_____||  \____//   \____//     \__ || 
  `----`   `-----`    `---`     `---`       -|_|| 
                                             `-`

Please enter what you see:

發送短信 : An Introduction to Echo Analysis : scattering theory and wave propagation