我一直尝试安装 steam，但只得到：
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:
steam:i386 : Depends: libgl1-mesa-dri:i386 (>= 17.3) but it is not going to be installed or
libtxc-dxtn0:i386 but it is not installable
Depends: libgl1-mesa-glx:i386 but it is not going to be installed
Depends: libgpg-error0:i386 (>= 1.10) but it is not going to be installed
Depends: libudev1:i386 but it is not going to be installed
Depends: libxcb-dri3-0:i386 (>= 1.11.1) but it is not going to be installed
Depends: libxinerama1:i386 (>= 2:1.1.1) but it is not going to be installed
Depends: libc6:i386 (>= 2.15) but it is not going to be installed
Depends: libstdc++6:i386 (>= 4.8) but it is not going to be installed
Depends: libx11-6:i386 but it is not going to be installed
Recommends: libxss1:i386 but it is not going to be installed
Recommends: mesa-vulkan-drivers:i386 but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
sudo apt update：
Hit:1 https://repo.steampowered.com/steam stable InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit:3 http://archive.canonical.com/ubuntu focal InRelease
Get:4 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Get:5 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Get:6 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
Reading package lists... Done
E: Release file for http://us.archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease is not valid yet (invalid for another 9h 59min 37s). Updates for this repository will not be applied.
E: Release file for http://us.archive.ubuntu.com/ubuntu/dists/focal-backports/InRelease is not valid yet (invalid for another 10h 0min 37s). Updates for this repository will not be applied.
E: Release file for http ://security.ubuntu.com/ubuntu/dists/focal-security/InRelease is not valid yet (invalid for another 9h 58min 57s). Updates for this repository will not be applied.
sudo apt upgrade：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.