当我在 Centos 上安装 mysql 时，出现以下错误：
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist mirrorlist.centos.org/?release=6&arch=x86_64&repo=os error was 14: PYCURL ERROR 22 - "The requested URL returned error: 403"
Error: Cannot find a valid baseurl for repo: base
yum有什么问题吗？