如何解决 Unable to locate package gcc-4.6-base:i386

  环境：ubuntu16.04(64bit)

root@mk-ThinkPad-T460:~/Downloads/disk1# apt install gcc-4.6-base:i386
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package gcc-4.6-base:i386
E: Couldn't find any package by glob 'gcc-4.6-base'
E: Couldn't find any package by regex 'gcc-4.6-base'

   当使用sudo apt-get upgrade,然后再使用sudo apt-get update之后还是无法找到对应的安装包时，需要手动添加源

我在中添加了2行/etc/apt/sources.list：

deb     http://archive.ubuntu.com/ubuntu/ trusty universe  
deb-src http://archive.ubuntu.com/ubuntu/ trusty universe