执行安装命令失败:vmregad@ubuntu:~$ sudo apt-get install python3-pipReading package lists... DoneBuilding dependency tree Reading state information... DoneE: Unable to locate package python3-pip软件源更新vmregad@ubuntu:~$ sudo apt updateIgn:1 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish InRelease Ign:2 http://security.ubuntu.com/ubuntu cuttlefish-security InRelease Ign:3 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-updates InReleaseErr:4 http://security.ubuntu.com/ubuntu cuttlefish-security Release 404 Not Found [IP: 91.189.91.38 80]Ign:5 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-backports InReleaseIgn:6 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-security InReleaseErr:7 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish Release Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443]Err:8 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-updates Release Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443]Err:9 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-backports Release Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443]Err:10 https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-security Release Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443]Ign:11 http://us.archive.ubuntu.com/ubuntu cuttlefish InReleaseIgn:12 http://us.archive.ubuntu.com/ubuntu cuttlefish-updates InReleaseIgn:13 http://us.archive.ubuntu.com/ubuntu cuttlefish-backports InReleaseErr:14 http://us.archive.ubuntu.com/ubuntu cuttlefish Release 404 Not Found [IP: 91.189.91.39 80]Err:15 http://us.archive.ubuntu.com/ubuntu cuttlefish-updates Release 404 Not Found [IP: 91.189.91.39 80]Err:16 http://us.archive.ubuntu.com/ubuntu cuttlefish-backports Release 404 Not Found [IP: 91.189.91.39 80]Reading package lists... DoneE: The repository 'http://security.ubuntu.com/ubuntu cuttlefish-security Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.E: The repository 'https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.E: The repository 'https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-updates Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.E: The repository 'https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-backports Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.E: The repository 'https://mirrors.tuna.tsinghua.edu.cn/ubuntu cuttlefish-security Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.E: The repository 'http://us.archive.ubuntu.com/ubuntu cuttlefish Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.E: The repository 'http://us.archive.ubuntu.com/ubuntu cuttlefish-updates Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.E: The repository 'http://us.archive.ubuntu.com/ubuntu cuttlefish-backports Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.软件源信息：sudo gedit /etc/apt/sources.listdeb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish main restricted universe multiverse# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish main restricted universe multiversedeb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish-updates main restricted universe multiverse# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish-updates main restricted universe multiversedeb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish-backports main restricted universe multiverse# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish-backports main restricted universe multiversedeb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish-security main restricted universe multiverse# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ cuttlefish-security main restricted universe multiverse#deb cdrom:[Ubuntu 18.10 _cuttlefish cuttlefish_ - Release amd64 (20181017.3)]/ cuttlefish main restricted# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to# newer versions of the distribution.deb http://us.archive.ubuntu.com/ubuntu/ cuttlefish main restricted# deb-src http://us.archive.ubuntu.com/ubuntu/ cuttlefish main restricted## Major bug fix updates produced after the final release of the## distribution.deb http://us.archive.ubuntu.com/ubuntu/ cuttlefish-updates main restricted# deb-src http://us.archive.ubuntu.com/ubuntu/ cuttlefish-updates main restricted## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu## team. Also, please note that software in universe WILL NOT receive any## review or updates from the Ubuntu security team.deb http://us.archive.ubuntu.com/ubuntu/ cuttlefish universe# deb-src http://us.archive.ubuntu.com/ubuntu/ cuttlefish universedeb http://us.archive.ubuntu.com/ubuntu/ cuttlefish-updates universe# deb-src http://us.archive.ubuntu.com/ubuntu/ cuttlefish-updates universe## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## multiverse WILL NOT receive any review or updates from the Ubuntu## security team.deb http://us.archive.ubuntu.com/ubuntu/ cuttlefish multiverse# deb-src http://us.archive.ubuntu.com/ubuntu/ cuttlefish multiversedeb http://us.archive.ubuntu.com/ubuntu/ cuttlefish-updates multiverse# deb-src http://us.archive.ubuntu.com/ubuntu/ cuttlefish-updates multiverse## N.B. software from this repository may not have been tested as## extensively as that contained in the main release, although it includes## newer versions of some applications which may provide useful features.## Also, please note that software in backports WILL NOT receive any review## or updates from the Ubuntu security team.deb http://us.archive.ubuntu.com/ubuntu/ cuttlefish-backports main restricted universe multiverse# deb-src http://us.archive.ubuntu.com/ubuntu/ cuttlefish-backports main restricted universe multiverse## Uncomment the following two lines to add software from Canonical's## 'partner' repository.## This software is not part of Ubuntu, but is offered by Canonical and the## respective vendors as a service to Ubuntu users.# deb http://archive.canonical.com/ubuntu cuttlefish partner# deb-src http://archive.canonical.com/ubuntu cuttlefish partnerdeb http://security.ubuntu.com/ubuntu cuttlefish-security main restricted# deb-src http://security.ubuntu.com/ubuntu cuttlefish-security main restricteddeb http://security.ubuntu.com/ubuntu cuttlefish-security universe# deb-src http://security.ubuntu.com/ubuntu cuttlefish-security universedeb http://security.ubuntu.com/ubuntu cuttlefish-security multiverse# deb-src http://security.ubuntu.com/ubuntu cuttlefish-security multiverse# This system was installed using small removable media# (e.g. netinst, live or single CD). The matching "deb cdrom"# entries were disabled at the end of the installation process.# For information about how to configure apt package sources,# see the sources.list(5) manual.