(classic)liu-xiao-guo@localhost:~$ sudo apt-get install curl
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  curl
0 upgraded, 1 newly installed, 0 to remove and 1 not upgraded.
Need to get 135 kB of archives.
After this operation, 297 kB of additional disk space will be used.
Err:1 http://localhost:9999/ubuntu-ports xenial-security/main armhf curl armhf 7.47.0-1ubuntu2.2
  Could not connect to localhost:9999 (127.0.0.1). - connect (111: Connection refused) [IP: 127.0.0.1 9999]
Err:1 http://localhost:9999/ubuntu-ports xenial-security/main armhf curl armhf 7.47.0-1ubuntu2.2
  Could not connect to localhost:9999 (127.0.0.1). - connect (111: Connection refused) [IP: 127.0.0.1 9999]
E: Failed to fetch http://localhost:9999/ubuntu-ports/pool/main/c/curl/curl_7.47.0-1ubuntu2.2_armhf.deb  Could not connect to localhost:9999 (127.0.0.1). - connect (111: Connection refused) [IP: 127.0.0.1 9999]

E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?