Ubuntu20.04换阿里源（解决安装build-essential失败问题）

背景：
在Ubuntu20.04 LTS上，需要使用gcc和g++编译器编译程序，在安装build-essential时报错。如下：

acl@ubuntu:~/test$ sudo apt install build-essential
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming

Ubuntu20.04换阿里源（解决安装build-essential失败问题）

背景：
在Ubuntu20.04 LTS上，需要使用gcc和g++编译器编译程序，在安装build-essential时报错。如下：

acl@ubuntu:~/test$ sudo apt install build-essential
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming