question about using System in Console project

Hello

If i have using System only, I can use Console.Write() but i can't use e.g. Linq.

If i have using System.Linq only, I can use Linq  but not Console.Write(). How come?

I thought that Linq would be added to System, or System assemblies would inherits from Linq assemblies.

How to read using System.Linq (from left to right or the inverse?). Why can't i do using Linq assuming i only need Linq?

Thanks