无法安装单声道

我目前卡住了，无法在我的 PC 上安装 mono-devel。我已经安装了单声道钥匙圈和 repo，但是每当我尝试安装它时，我都会得到这个：

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:
 mono-devel : Depends: mono-runtime (>= 3.0~) but it is not going to be installed
              Depends: libc6 (>= 2.31) but 2.28-10 is to be installed or
                       libc6.1 (>= 2.31) but it is not installable or
                       libc0.1 (>= 2.31) but it is not installable
              Depends: libglib2.0-0 (>= 2.64.6) but 2.58.3-2+deb10u2 is to be installed
              Depends: libmono-cecil-private-cil (>= 6.12.0.122) but it is not going to be installed
              Depends: libmono-cecil-private-cil (< 6.12.0.123) but it is not going to be installed
              Depends: libmono-codecontracts4.0-cil (>= 1.0) but it is not going to be installed
              Depends: libmono-compilerservices-symbolwriter4.0-cil (>= 3.6.0) but it is not going to be installed
              Depends: libmono-corlib4.5-cil (>= 4.0.0~alpha1) but it is not going to be installed
              Depends: libmono-peapi4.0a-cil (>= 3.2.8) but it is not going to be installed
              Depends: libmono-relaxng4.0-cil (>= 2.10.1) but it is not going to be installed
              Depends: libmono-security4.0-cil (>= 3.0.6) but it is not going to be installed
              Depends: libmono-system-configuration-install4.0-cil (>= 1.0) but it is not going to be installed
              Depends: libmono-system-configuration4.0-cil (>= 4.0.0~alpha1) but it is not going to be installed
              Depends: libmono-system-core4.0-cil (>= 4.0.0~alpha1) but it is not going to be installed
              Depends: libmono-system-data4.0-cil (>= 4.0.0~alpha1) but it is not going to be installed
              Depends: libmono-system-drawing4.0-cil (>= 3.0.6) but it is not going to be installed
              Depends: libmono-system-io-compression-filesystem4.0-cil (>= 3.2.1) but it is not going to be installed
              Depends: libmono-system-runtime-serialization4.0-cil (>= 4.0.0~alpha1) but it is not going to be installed
              Depends: libmono-system-runtime4.0-cil (>= 2.10.1) but it is not going to be installed
              Depends: libmono-system-security4.0-cil (>= 1.0) but it is not going to be installed
              Depends: libmono-system-servicemodel4.0a-cil (>= 3.2.3) but it is not going to be installed
              Depends: libmono-system-web-services4.0-cil (>= 1.0) but it is not going to be installed
              Depends: libmono-system-xml-linq4.0-cil (>= 3.0.6) but it is not going to be installed
              Depends: libmono-system-xml4.0-cil (>= 3.12.0) but it is not going to be installed
              Depends: libmono-system4.0-cil (>= 4.0.0~alpha1) but it is not going to be installed
              Depends: mono-mcs (= 6.12.0.122-0xamarin1+ubuntu2004b1) but it is not going to be installed
              Depends: mono-roslyn (= 6.12.0.122-0xamarin1+ubuntu2004b1) but it is not going to be installed
              Depends: mono-gac (= 6.12.0.122-0xamarin1+ubuntu2004b1) but it is not going to be installed
              Depends: mono-xbuild (= 6.12.0.122-0xamarin1+ubuntu2004b1) but it is not going to be installed
              Depends: libmono-cil-dev (= 6.12.0.122-0xamarin1+ubuntu2004b1) but it is not going to be installed
              Depends: libmono-2.0-dev (>= 6.12.0.122-0xamarin1+ubuntu2004b1) but it is not going to be installed
              Depends: libmono-2.0-dev (< 6.12.0.122-0xamarin1+ubuntu2004b1.1~) but it is not going to be installed
              Depends: ca-certificates-mono (= 6.12.0.122-0xamarin1+ubuntu2004b1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

请帮忙，谢谢大家。