http://appleinsider.com/articles/18/01/29/video-how-to-downgrade-from-macos-high-sierra-to-sierra
origin - http://www.pipiscrew.com/2018/01/how-to-downgrade-from-macos-high-sierra-to-sierra/ how-to-downgrade-from-macos-high-sierra-to-sierra
http://appleinsider.com/articles/18/01/29/video-how-to-downgrade-from-macos-high-sierra-to-sierra
origin - http://www.pipiscrew.com/2018/01/how-to-downgrade-from-macos-high-sierra-to-sierra/ how-to-downgrade-from-macos-high-sierra-to-sierra