how to make apt-get install prefer source from local iso?
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if there are lots of sources in sourcelist, but i want apt-get to prefer source from local iso, rather than remote mirror, even when remote package is newer than local iso, i wannt apt-get to choose local iso, what i should do in order to make it works as i want?           


this is my configuration of /etc/apt/source.list

deb file:///home/jack/dsk/ lucid main restricted
deb http:// us.archive.ubuntu.com/ubuntu/ lucid main restricted
deb-src http: //us.archive.ubuntu.com/ubuntu/ lucid main restricted

i run apt-get install ubuntu-desktop, it seems apt-get try to download package from remote mirror:( this is not the thing i want:( 
i am sure ubuntu-desktop package is in my local iso mirror :( so how to make apt-get choose to install the package from dsk/pool/main/u/ubuntu-meta/ubuntu-desktop_1.197_amd64.deb rather than from http: // us.archive.ubuntu.com/ubuntu/ lucid-updates/main libc6 2.11.1-0ubuntu7.10 ?



find dsk/ | grep ubuntu-desktop
dsk/pool/main/u/ubuntu-meta/ubuntu-desktop_1.197_amd64.deb

After this operation, 2,191MB of additional disk space will be used.
Get:1 http: // us.archive.ubuntu.com/ubuntu/ lucid-updates/main libc6 2.11.1-0ubuntu7.10 [4,389kB]