> 适用于 **Ubuntu 26.04 LTS**（代号 `resolute`）。
> 不确定自己的版本？先执行 `cat /etc/os-release`，看 `VERSION_CODENAME` 是不是 `resolute`。

```bash
sudo tee /etc/apt/sources.list.d/ubuntu.sources <<'EOF'
Types: deb
URIs: https://mirrors.tuna.tsinghua.edu.cn/ubuntu
Suites: resolute resolute-updates resolute-backports
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

# Types: deb-src
# URIs: https://mirrors.tuna.tsinghua.edu.cn/ubuntu
# Suites: resolute resolute-updates resolute-backports
# Components: main restricted universe multiverse
# Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

Types: deb
URIs: https://mirrors.tuna.tsinghua.edu.cn/ubuntu/
Suites: resolute-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
EOF
```

换源后执行 `sudo apt update` 刷新软件列表，之后即可正常 `sudo apt install gcc g++`。