發送短信

數:

提供者:

CAPTCHA:

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

Please enter what you see:

發送短信 : Ultrasonic wave propagation in non homogeneous media