网络源

cat /etc/yum.repo.d/ 确定版本型号 图中剩下的步骤是移动之前的文件，将其移动到bak的备份目录

新建阿里云的仓库，输入以下
[appstream]
name=appstream
baseurl=https://mirrors.aliyun.com/centos-stream/9-stream/AppStream/x86_64/os/

baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-stream/9-stream/AppStream/x86_64/os/

gpgcheck=0
[baseos]
name=baseos
baseurl=https://mirrors.aliyun.com/centos-stream/9-stream/BaseOS/x86_64/os/

baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-stream/9-stream/BaseOS/x86_64/os/

gpgcheck=0

如图排版
清理原缓存，重新进行注册，如下图

yum install gcc 安装次语言编译器
gcc -v 查看安装是否成功
yum repolist 查看仓库