Ubnutu下安装个g++，build-essential出现依赖关系的原因

Ubnutu下安装个g++，build-essential出现依赖关系的原因

在Ubnutu下输入 ：sudo apt-get install build-essential

出现下列错误

Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

Since you only requested a single operation it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
build-essential: Depends: g++ (>= 4:4.1.1) but it is not going to be installed
E: Broken packages

版本 ：Ubuntu 7.04

原因：
更新源出现了问题！