The dependency "EntityFramework": "6.1.3" does not support framework NetCorApp, Version = V1.0

Hi,

I am using a generic repository

using System.Data.Entity;
...

public class GenericRepository<T>:IGenericRepository<T> where T : class
{
    private NorthwindEntities db = null;
    private DbSet<T> table = null;
    public GenericRepository(NorthwindEntities db)
    {
        this.db = db;
        table = db.Set<T>();
    }

 
     public T SelectByID(object id)
    {
        return table.Find(id);
    }

...
}

here "table.Find(id)" would need a library of "System.Data.Entity", which is in the package "EntityFramework". After I installed the "EntityFramework" package, I got a

The dependency "EntityFramework": "6.1.3" does not support framework NetCorApp, Version = V1.0 

I have tried "EntityFrameworkCore" package, but it doesn't know "System.Data.Entity". What should I do?