thanks the sudo command worked.And there's more
When i run an update, it tells me:
"Not enough free disk space
The upgrade needs a total of 413M free space on disk '/'. Please free at least an additional 237M of disk space on '/'. Empty your trash and remove temporary packages of former installations using 'sudo apt-get clean'."
my partitions is not full but it tells me this. and when i try the "sudo apt-get clean" command, nothing happened!