通常，安装具有当前未安装的依赖项的包将让 apt 确认这是否是需要的在继续安装之前：
$ sudo apt install gnome-terminal
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
gnome-terminal-data gnome-user-guide libhyphen0 libjavascriptcoregtk-4.0-18 libnautilus-extension1a libwebkit2gtk-4.0-37 libwebkit2gtk-4.0-37-gtk2
libyelp0 yelp yelp-xsl
The following NEW packages will be installed:
gnome-terminal gnome-terminal-data gnome-user-guide libhyphen0 libjavascriptcoregtk-4.0-18 libnautilus-extension1a libwebkit2gtk-4.0-37
libwebkit2gtk-4.0-37-gtk2 libyelp0 yelp yelp-xsl
0 upgraded, 11 newly installed, 0 to remove and 0 not upgraded.
Need to get 23.5 MB of archives.
After this operation, 115 MB of additional disk space will be used.
Do you want to continue? [Y/n]
然而，几分钟前，我运行了完全相同的命令，并且无需询问就安装了 gnome-terminal 及其依赖项：
$ sudo apt install gnome-terminal
Reading package lists... Done
Building dependency tree... 50%
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
gnome-terminal-data gnome-user-guide libhyphen0 libjavascriptcoregtk-4.0-18 libnautilus-extension1a libwebkit2gtk-4.0-37 libwebkit2gtk-4.0-37-gtk2
libyelp0 yelp yelp-xsl
The following NEW packages will be installed:
gnome-terminal gnome-terminal-data gnome-user-guide libhyphen0 libjavascriptcoregtk-4.0-18 libnautilus-extension1a libwebkit2gtk-4.0-37
libwebkit2gtk-4.0-37-gtk2 libyelp0 yelp yelp-xsl
0 upgraded, 11 newly installed, 0 to remove and 0 not upgraded.
Need to get 23.5 MB of archives.
After this operation, 115 MB of additional disk space will be used.
Get:1 http://ports.ubuntu.com/ubuntu-ports xenial-updates/main armhf libnautilus-extension1a armhf 1:3.18.4.is.3.14.3-0ubuntu6 [51.9 kB]
Get:2 http://ports.ubuntu.com/ubuntu-ports xenial/main armhf gnome-terminal-data all 3.18.3-1ubuntu1 [41.0 kB]
Get:3 http://ports.ubuntu.com/ubuntu-ports xenial/main armhf gnome-terminal armhf 3.18.3-1ubuntu1 [148 kB]
...
apt 为什么要这样做？