gcc:
  Installed: 4:4.8.2-1ubuntu6
  Candidate: 4:4.8.2-1ubuntu6
  Version table:
 *** 4:4.8.2-1ubuntu6 0
        500 http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ trusty/main amd64 Packages
        100 /var/lib/dpkg/status