尝试安装“unity-tweak-tool”并得到：
$ sudo apt-get install unity-tweak-tool
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.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
unity-tweak-tool : Depends: unity-webapps-common but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
进行了一些研究并运行：
sudo apt-get --fix-broken install
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 to upgrade, 0 to newly install, 0 to remove and 1 not to upgrade.
然后
sudo apt-get dist-upgrade
但没有效果，所以仍然有一个问题，那就是如何回溯到依赖关系的原因。所以尝试了 aptitude 并得到：
sudo aptitude install unity-tweak-tool
The following NEW packages will be installed:
libhardware2{a} libhybris{a} libhybris-common1{a} libmedia1{a}
liboxideqt-qmlplugin{a} liboxideqtcore0{ab} liboxideqtquick0{a}
libqt5organizer5{ab} libubuntugestures5{ab} libubuntutoolkit5{ab}
libunity-webapps0{a} qml-module-ubuntu-components{ab}
qml-module-ubuntu-layouts{ab} qml-module-ubuntu-test{ab}
qml-module-ubuntu-web{a} qtdeclarative5-ubuntu-ui-toolkit-plugin{a}
unity-tweak-tool unity-webapps-common{a} unity-webapps-qml{a}
unity-webapps-service{a} webapp-container{ab} webbrowser-app{ab}
0 packages upgraded, 22 newly installed, 0 to remove and 0 not to upgrade.
Need to get 36.9 MB of archives. After unpacking 145 MB will be used.
The following packages have unmet dependencies:
qml-module-ubuntu-test : Depends: qtbase-abi-5-5-1 which is a virtual package, provided by:
- libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed. - libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed.
liboxideqtcore0 : Depends: qtbase-abi-5-5-1 which is a virtual package, provided by:
- libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed. - libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed.
libqt5organizer5 : Depends: qtbase-abi-5-5-1 which is a virtual package, provided by:
- libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed. - libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed.
webapp-container : Depends: qtbase-abi-5-5-1 which is a virtual package, provided by:
- libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed. - libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed.
Depends: qtdeclarative-abi-5-5-0 which is a virtual package, provided by:
- libqt5qml5, but 5.10.0-0neon+16.04+xenial+build36 is installed.
qml-module-ubuntu-layouts : Depends: qtdeclarative-abi-5-5-0 which is a virtual package, provided by:
- libqt5qml5, but 5.10.0-0neon+16.04+xenial+build36 is installed.
qml-module-ubuntu-components : Depends: qtbase-abi-5-5-1 which is a virtual package, provided by:
- libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed. - libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed.
Depends: qtdeclarative-abi-5-5-0 which is a virtual package, provided by:
- libqt5qml5, but 5.10.0-0neon+16.04+xenial+build36 is installed.
libubuntutoolkit5 : Depends: qtbase-abi-5-5-1 which is a virtual package, provided by:
- libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed. - libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed.
webbrowser-app : Depends: qtbase-abi-5-5-1 which is a virtual package, provided by:
- libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed. - libqt5core5a, but 5.10.0+dfsg-2+16.04+xenial+build46 is installed.
Depends: qtdeclarative-abi-5-5-0 which is a virtual package, provided by:
- libqt5qml5, but 5.10.0-0neon+16.04+xenial+build36 is installed.
libubuntugestures5 : Depends: qtdeclarative-abi-5-5-0 which is a virtual package, provided by:
- libqt5qml5, but 5.10.0-0neon+16.04+xenial+build36 is installed.
The following actions will resolve these dependencies:
Keep the following packages at their current version:
1) liboxideqt-qmlplugin [Not Installed]
2) liboxideqtcore0 [Not Installed]
3) liboxideqtquick0 [Not Installed]
4) libqt5organizer5 [Not Installed]
5) libubuntugestures5 [Not Installed]
6) libubuntutoolkit5 [Not Installed]
7) libunity-webapps0 [Not Installed]
8) qml-module-ubuntu-components [Not Installed]
9) qml-module-ubuntu-layouts [Not Installed]
10) qml-module-ubuntu-test [Not Installed]
11) qml-module-ubuntu-web [Not Installed]
12) qtdeclarative5-ubuntu-ui-toolkit-plugin [Not Installed]
13) unity-tweak-tool [Not Installed]
14) unity-webapps-common [Not Installed]
15) unity-webapps-qml [Not Installed]
16) unity-webapps-service [Not Installed]
17) webapp-container [Not Installed]
18) webbrowser-app [Not Installed]
Accept this solution? [Y/n/q/?] Y
No packages will be installed, upgraded, or removed.
0 packages upgraded, 0 newly installed, 0 to remove and 0 not to upgrade.
Need to get 0 B of archives. After unpacking 0 B will be used.
尝试通过手动安装来解决依赖关系时，libqt5core5a在运行时aptitude install liboxideqtquick0想要卸载时也遇到了“ ”的问题libmlt++3, libmlt6, libqt5webchannel5, melt, openshot, python-mlt and qt5-gtk-platformtheme。
非常感谢任何帮助找到解决方案的帮助
。
================================================================================
进一步请求更多信息：
由于 pkg 更新存在一些重大滞后，因此添加了以下内容以获取最新版本的 pkg 或安装不在主存储库中的 pkg。因此，为了全面起见，我包括了以下内容。
我使用脚本来提取 repos 和 PPA 的列表：
以下是不言自明的：
'http://archive.ubuntu.com/ubuntu xenial main restricted'
'http://archive.ubuntu.com/ubuntu xenial-updates main restricted'
'http://archive.ubuntu.com/ubuntu xenial universe'
'http://archive.ubuntu.com/ubuntu xenial-updates universe'
'http://archive.ubuntu.com/ubuntu xenial multiverse'
'http://archive.ubuntu.com/ubuntu xenial-updates multiverse'
'http://archive.ubuntu.com/ubuntu xenial-backports main restricted universe multiverse'
'http://archive.canonical.com/ubuntu xenial partner'
'http://archive.ubuntu.com/ubuntu xenial-security main restricted'
'http://archive.ubuntu.com/ubuntu xenial-security universe'
'http://archive.ubuntu.com/ubuntu xenial-security multiverse'
'http://deb.torproject.org/torproject.org xenial main'
'https://dl.winehq.org/wine-builds/ubuntu/ xenial main'
'https://download.virtualbox.org/virtualbox/debian xenial contrib'
这些是为了获取最新版本或添加功能：
ppa:stebbins/handbrake-releases
ppa:maarten-baert/simplescreenrecorder
ppa:webupd8team/nemo3 # latest version of nemo file browser
ppa:linrunner/tlp
ppa:mc3man/mpv-tests
ppa:elementary-os/stable
ppa:bablu-boy/nutty
ppa:jfi/ppa
ppa:audio-recorder/ppa
ppa:noobslab/themes
ppa:hda-me/zulucrypt
ppa:scribus/ppa
ppa:plushuang-tw/uget-stable
ppa:mc3man/xerus-media
ppa:unit193/encryption
ppa:noobslab/icons
ppa:jeffreyratcliffe/ppa
'http://repo.vivaldi.com/stable/deb/ stable main' # Vivaldi Web Browser
============
现在是 PPA 中已安装 pkg 的详细列表，我使用以下脚本提取它们：
apt-cache policy $(dpkg --get-selections | grep -v deinstall$ | awk '{ print $1 }') | perl -e '@a = <>; $a=join("", @a); $a =~ s/\n(\S)/\n\n$1/g; @packages = split("\n\n", $a); foreach $p (@packages) {print "$1: $2\n" if $p =~ /^(.*?):.*?500 http:\/\/ppa\.launchpad\.net\/(.*?)\s/s}'
。
albatross-theme: noobslab/themes/ubuntu
ashes-theme: noobslab/themes/ubuntu
audio-recorder: audio-recorder/ppa/ubuntu
cinnamon-l10n: webupd8team/nemo3/ubuntu
com.github.babluboy.nutty: bablu-boy/nutty/ubuntu
contractor: elementary-os/stable/ubuntu
cryptsetup: unit193/encryption/ubuntu
cryptsetup-bin: unit193/encryption/ubuntu
faba-icon-theme: noobslab/icons/ubuntu
faenza-icon-theme: noobslab/icons/ubuntu
faience-icon-theme: noobslab/icons/ubuntu
ffmpeg: mc3man/xerus-media/ubuntu
gir1.2-nemo-3.0: webupd8team/nemo3/ubuntu
gscan2pdf: jeffreyratcliffe/ppa/ubuntu
handbrake-cli: stebbins/handbrake-releases/ubuntu
handbrake-gtk: stebbins/handbrake-releases/ubuntu
i965-va-driver: mc3man/mpv-tests/ubuntu
i965-va-driver: mc3man/mpv-tests/ubuntu
libavcodec-extra: mc3man/xerus-media/ubuntu
libavcodec-extra57: mc3man/xerus-media/ubuntu
libavcodec-ffmpeg-extra56: mc3man/xerus-media/ubuntu
libavdevice-ffmpeg56: mc3man/xerus-media/ubuntu
libavdevice57: mc3man/xerus-media/ubuntu
libavfilter-ffmpeg5: mc3man/xerus-media/ubuntu
libavfilter6: mc3man/xerus-media/ubuntu
libavformat-ffmpeg56: mc3man/xerus-media/ubuntu
libavformat57: mc3man/xerus-media/ubuntu
libavresample-ffmpeg2: mc3man/xerus-media/ubuntu
libavresample3: mc3man/xerus-media/ubuntu
libavutil-ffmpeg54: mc3man/xerus-media/ubuntu
libavutil55: mc3man/xerus-media/ubuntu
libbasicusageenvironment1: mc3man/xerus-media/ubuntu
libcryptsetup4: unit193/encryption/ubuntu
libfdk-aac1: mc3man/xerus-media/ubuntu
libglib-object-introspection-perl: jeffreyratcliffe/ppa/ubuntu
libgoocanvas2-perl: jeffreyratcliffe/ppa/ubuntu
libgranite-common: elementary-os/stable/ubuntu
libgranite4: elementary-os/stable/ubuntu
libgroupsock8: mc3man/xerus-media/ubuntu
libgtk3-perl: jeffreyratcliffe/ppa/ubuntu
libgtk3-simplelist-perl: jeffreyratcliffe/ppa/ubuntu
libimage-sane-perl: jeffreyratcliffe/ppa/ubuntu
liblirc-client0: mc3man/xerus-media/ubuntu
liblircclient0: mc3man/xerus-media/ubuntu
liblivemedia58: mc3man/xerus-media/ubuntu
libmysofa: mc3man/mpv-tests/ubuntu
libnemo-extension1: webupd8team/nemo3/ubuntu
libpostproc-ffmpeg53: mc3man/xerus-media/ubuntu
libpostproc54: mc3man/xerus-media/ubuntu
libqxp-0.0-0: scribus/ppa/ubuntu
libswresample-ffmpeg1: mc3man/xerus-media/ubuntu
libswresample2: mc3man/xerus-media/ubuntu
libswscale-ffmpeg3: mc3man/xerus-media/ubuntu
libswscale4: mc3man/xerus-media/ubuntu
libusageenvironment3: mc3man/xerus-media/ubuntu
libva-drm1: mc3man/mpv-tests/ubuntu
libva-drm1: mc3man/mpv-tests/ubuntu
libva-x11-1: mc3man/mpv-tests/ubuntu
libva-x11-1: mc3man/mpv-tests/ubuntu
libva1: mc3man/mpv-tests/ubuntu
libva1: mc3man/mpv-tests/ubuntu
libvlc-bin: mc3man/xerus-media/ubuntu
libvlc5: mc3man/xerus-media/ubuntu
libvlccore8: mc3man/xerus-media/ubuntu
libx264-148: mc3man/xerus-media/ubuntu
libx264-152: mc3man/xerus-media/ubuntu
libx265-130: mc3man/xerus-media/ubuntu
libx265-146: mc3man/xerus-media/ubuntu
libxapp1: webupd8team/nemo3/ubuntu
libzimg2: mc3man/xerus-media/ubuntu
libzmf-0.0-0: scribus/ppa/ubuntu
libzulucrypt1: hda-me/zulucrypt/ubuntu
mpv: mc3man/mpv-tests/ubuntu
nemo: webupd8team/nemo3/ubuntu
nemo-data: webupd8team/nemo3/ubuntu
nemo-dropbox: webupd8team/nemo3/ubuntu
nemo-fileroller: webupd8team/nemo3/ubuntu
nemo-media-columns: webupd8team/nemo3/ubuntu
numix-folders: noobslab/icons/ubuntu
numix-gtk-theme: noobslab/themes/ubuntu
numix-icon-theme: noobslab/icons/ubuntu
numix-icon-theme-circle: noobslab/icons/ubuntu
numix-icon-theme-square: noobslab/icons/ubuntu
nutty: bablu-boy/nutty/ubuntu
psensor: jfi/ppa/ubuntu
psensor-common: jfi/ppa/ubuntu
python-nemo: webupd8team/nemo3/ubuntu
scribus-ng: scribus/ppa/ubuntu
scribus-ng-data: scribus/ppa/ubuntu
scribus-ng-doc: scribus/ppa/ubuntu
simplescreenrecorder: maarten-baert/simplescreenrecorder/ubuntu
simplescreenrecorder-lib: maarten-baert/simplescreenrecorder/ubuntu
smplayer: mc3man/xerus-media/ubuntu
smplayer-themes: mc3man/xerus-media/ubuntu
smtube: mc3man/xerus-media/ubuntu
tlp: linrunner/tlp/ubuntu
tlp-rdw: linrunner/tlp/ubuntu
tp-smapi-dkms: linrunner/tlp/ubuntu # TLP Power Management, for Lenovo ThinkPad laptop
uget: plushuang-tw/uget-stable/ubuntu
va-driver-all: mc3man/mpv-tests/ubuntu
va-driver-all: mc3man/mpv-tests/ubuntu
veracrypt: unit193/encryption/ubuntu
vlc: mc3man/xerus-media/ubuntu
vlc-bin: mc3man/xerus-media/ubuntu
vlc-data: mc3man/xerus-media/ubuntu
vlc-l10n: mc3man/xerus-media/ubuntu
vlc-plugin-base: mc3man/xerus-media/ubuntu
vlc-plugin-notify: mc3man/xerus-media/ubuntu
vlc-plugin-qt: mc3man/xerus-media/ubuntu
vlc-plugin-samba: mc3man/xerus-media/ubuntu
vlc-plugin-skins2: mc3man/xerus-media/ubuntu
vlc-plugin-video-output: mc3man/xerus-media/ubuntu
vlc-plugin-video-splitter: mc3man/xerus-media/ubuntu
vlc-plugin-visualization: mc3man/xerus-media/ubuntu
vokoscreen: mc3man/xerus-media/ubuntu
xapps-common: webupd8team/nemo3/ubuntu
zulucrypt-cli: hda-me/zulucrypt/ubuntu
zulucrypt-gui: hda-me/zulucrypt/ubuntu