when i tried to run a command as my friend did : yum list-security, it seems not such command options.
so confused, but after i checked with my old friend: google, i got the answer from a corner.
here is the solution.
we need to edit the /etc/yum.conf, and set the plubings=1 as bellow:
***********************
cat /etc/yum.conf
[main]
cachedir=/var/cache/yum
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
distroverpkg=redhat-release
tolerant=1
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
原文：http://dogrider.blog.51cto.com/771879/1719216