我是 Linux 社区的新用户，仍然在玩这个系统，但我不知道我的软件中心为何丢失了。
我尝试更新和升级，但似乎无法重新安装丢失的应用程序。
$ sudo apt install software-center
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:
bind9-host : Depends: libbind9-140 (= 1:9.10.3.dfsg.P4-8ubuntu1.7) but it is not going to be installed
Depends: libdns162 (= 1:9.10.3.dfsg.P4-8ubuntu1.7) but it is not going to be installed
Depends: libisccfg140 (= 1:9.10.3.dfsg.P4-8ubuntu1.7) but it is not going to be installed
libical1a : Depends: tzdata but it is not going to be installed
libpython-stdlib : Depends: libpython2.7-stdlib (>= 2.7.11-1~) but it is not going to be installed
python2.7 : Depends: libpython2.7-stdlib (= 2.7.12-1ubuntu0~16.04.1) but it is not going to be installed
python3.5-minimal : Depends: libpython3.5-minimal (= 3.5.2-2ubuntu0~16.04.1) but it is not going to be installed
Recommends: python3.5 but it is not going to be installed
software-center : Depends: python (>= 2.7.1-0ubuntu2) but it is not going to be installed
Depends: aptdaemon (>= 0.40) but it is not going to be installed
Depends: software-center-aptdaemon-plugins but it is not going to be installed
Depends: humanity-icon-theme but it is not going to be installed
Depends: gir1.2-gtk-3.0 but it is not going to be installed
Depends: gir1.2-webkit-3.0 but it is not going to be installed
Depends: python-gi but it is not going to be installed
Depends: python-gi-cairo but it is not going to be installed
Depends: python-xapian but it is not going to be installed
Depends: python-apt (>= 0.8.3ubuntu4) but it is not going to be installed
Depends: python-aptdaemon (>= 0.40) but it is not going to be installed
Depends: python-aptdaemon.gtk3widgets but it is not going to be installed
Depends: python-dbus but it is not going to be installed
Depends: python-defer but it is not going to be installed
Depends: policykit-1
Depends: policykit-1-gnome but it is not going to be installed or
policykit-1-kde but it is not installable
Depends: python-xdg but it is not going to be installed
Depends: ubuntu-sso-client-gtk but it is not going to be installed
Depends: python-piston-mini-client (>= 0.1+bzr29) but it is not going to be installed
Depends: oneconf (>= 0.2.6) but it is not going to be installed
Depends: python-debtagshw but it is not going to be installed
Depends: ubuntu-extras-keyring but it is not going to be installed
Recommends: lsb-release but it is not going to be installed
Recommends: gir1.2-launchpad-integration-3.0 but it is not going to be installed
Recommends: apt-xapian-index (>= 0.38ubuntu1) but it is not going to be installed
Recommends: update-notifier but it is not going to be installed
Recommends: software-properties-gtk but it is not going to be installed
Recommends: sessioninstaller but it is not going to be installed
Recommends: xz-lzma but it is not going to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.