yum -y install python-devel的时候报错如图：
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=6&arch=i386&repo=extras&infra=stock error was
12: Timeout on http://mirrorlist.centos.org/?release=6&arch=i386&repo=extras&infra=stock: (28, 'Operation too slow. Less than 1 bytes/sec transfered the last 30 seconds')
2.解决办法：
