Warning: file_put_contents(): Only 0 of 4886 bytes written, possibly out of free disk space in /home/www/wwwroot/zidian/001308.com/index.php on line 55 欧美一区二区在线观看,亚洲一日国产日韩欧美
Positive frequencies are produced by anticlockwise rotation and negative frequencies by clockwise rotation. 正頻率是用逆時(shí)針旋轉(zhuǎn)來(lái)產(chǎn)生，而負(fù)頻率是用順時(shí)針旋轉(zhuǎn)來(lái)產(chǎn)生。