sudo当我尝试通过 Debian 8.2安装时，aptitude install sudo出现错误：No candidate version found for sudo。源列表是标准的。
这是来源列表：
deb http://httpredir.debian.org/debian jessie main
deb-src http://httpredir.debian.org/debian jessie main
deb http://httpredir.debian.org/debian jessie-updates main
deb-src http://httpredir.debian.org/debian jessie-updates main
deb http://security.debian.org/ jessie/updates main
deb-src http://security.debian.org/ jessie/updates main