ubuntu 9.04中执行apt-get install build-essential出现的问题
liang@ubuntu:~$ sudo apt-get install build-essential
[sudo] password for liang: 
Reading package lists... Done
Building dependency tree  
Reading state information... Done
The following extra packages will be installed:
  dpkg-dev g++ g++-4.3 libstdc++6-4.3-dev patch
Suggested packages:
  debian-keyring g++-multilib g++-4.3-multilib gcc-4.3-doc libstdc++6-4.3-dbg
  libstdc++6-4.3-doc diff-doc
The following NEW packages will be installed:
  build-essential dpkg-dev g++ g++-4.3 libstdc++6-4.3-dev patch
0 upgraded, 6 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/6270kB of archives.
After this operation, 21.4MB of additional disk space will be used.
Do you want to continue [Y/n]? y
Media change: please insert the disc labeled
 'Ubuntu 9.04 _Jaunty Jackalope_ - Release i386 (20090420.1)'
in the drive '/cdrom/' and press enter


据说要在软件源找到有cdrom那行注释掉可是我的找不到啊？
勾掉system里的软件源中的那个CD-ROM/DVD后执行不了sudo apt-get install build-essential？求解！！！



------解决方案--------------------
ubuntu 1年半的支持时间，9.04在源理都没了吧……得用old-release了

这时候图形化的配置源工具没任何鸟用了，直接删掉/etc/apt/source.lst全部内容重新写一个源……