当我升级时，它会卡在这里：
user@plato:~# sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
bind9-host coreutils cpio curl dnsutils libbind9-90 libc-bin libc-dev-bin
libc6 libc6-dev libcgmanager0 libcurl3 libcurl3-gnutls libdns100
libdrm-intel1 libdrm-nouveau2 libdrm-radeon1 libdrm2 libisc95 libisccc90
libisccfg90 libjasper1 liblwres90 libplymouth2 libsepol1 libssl-dev
libssl-doc libssl1.0.0 linux-libc-dev mime-support multiarch-support ntp
ntpdate openssl plymouth plymouth-theme-ubuntu-text python3-distupgrade
ubuntu-release-upgrader-core unzip
39 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 16.0 …