Left join 2 or more tables with 1-n relationship

context.TableA
       .GroupJoin(context.TableB,
           a => a.Id,
           b => b.IdA,
           (a, b) => new { a, b = b.DefaultIfEmpty() }
       )
       .SelectMany(s => s.b, (s, b) => {
           Stuff = b.Stuff,
       })

{ Stuff = b.Stuff, Stuff2 = c.Stuff2 }