更新yum源：
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.bak1
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
yum makecache
参考链接：https://blog.csdn.net/y87329396/article/details/51357122
安装flash:
https://get.adobe.com/cn/flashplayer/下载linux版
rpm -ivh adobe-release-x86_64-1.0-1.noarch.rpm
yum install flash-plugin
参考链接：https://blog.csdn.net/lafeedfh/article/details/52316420