更換軟件源瘦馍，/etc/apt/source.list之后，安裝軟件不成功會顯示you have held broken packages嚎研，使用apt-get remove <package>將之前的包移除除盏，然后重新安裝
推薦使用網(wǎng)易的源，速度杠杠的（之前倒是找到過一個阿里云源儒飒，有一個url無法訪問）
deb http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
sudo apt-get install <package>安裝時(shí)候顯示lock不可用，使用 ps -aux | grep apt, kill掉相關(guān)進(jìn)程即可
