无法安装Ruby的sass gem

我正在尝试安装ruby的gem sass。我先运行了Ruby安装，然后： gem安装sass。但我得到了一个错误：

C:\Windows\system32>gem安装sass 错误：在任何存储库中都找不到有效的gem'sass'>=0

知道那可能是什么吗

谢谢

Update.
The connad: gem sources --add https://rubygems.org/ fails:
C:\Windows\system32>gem sources --add https://rubygems.org/
Error fetching https://rubygems.org/:
Errno::ETIMEDOUT: A connection attempt failed because the connected party 
did not properly respond after a period of time, or established connection failed 
because connected host has failed to respond. - connect(2) for "api.rubygems.org" 
port 443 (https://api.rubygems.org/specs.4.8.gz)

它必须是我们用来访问Internet的代理设置。可以让Ruby遵守这些设置吗

更新2

C:\Windows\system32>gem sources --add http://rubygems.org/
https://rubygems.org is recommended for security over http://rubygems.org/

Do you want to add this insecure source? [yn]  y
Error fetching http://rubygems.org/:
        Errno::ETIMEDOUT: A connection attempt failed because the connected part
y did not properly respond after a period of time, or established connection fai
led because connected host has failed to respond. - connect(2) for "api.rubygems
.org" port 80 (http://api.rubygems.org/specs.4.8.gz)

做

---

然后再试一次

gem sources的结果是什么sc:\Windows\system32>gem sources***CURRENT sources***顺便问一下，你能访问rubygems.org吗？traceroute rubygems.org traceroute rubygems.org给出一个错误，traceroute不是命令。tracert rubygems.org跟踪路由到rubygems.org[151.101.64.70]最多30跳：1***请求超时。

gem sources --add https://rubygems.org/