Q:
A： 源出问题，修改源：进入源：sudo vi sources.list，将下列内容替换sources.list中的内容，并保存
deb http://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe
sources.list替换完后，重新执行sudo apt-get update
而出现此问题的原因是因为可能是有另外一个程序正在运行，导致资源被锁不可用。而导致资源被锁的原因，可能是上次 安装时没正常完成，而导致出现此状况。
解决办法：在终端敲入这两句命令：
sudo rm /var/lib/apt/lists/lock
再继续安装就好了