Я установил Visual Studio 2013, но что бы я ни делал, я не могу установить пакет Entity Framework
The source at nuget.org [https://www.nuget.org/api/v2/] is unreachable. Falling back to NuGet Local Cache at C:\Users\mohammad\AppData\Local\NuGet\Cache
Install-Package : Unable to find package 'EntityFramework'.
At line:1 char:1
+ Install-Package EntityFramework
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Install-Package], InvalidOperationException
+ FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand
------------------------------------------------------------------------