Let (C,E, s) be an extriangulated category with a proper class ? of
E-triangles. In this paper, we first introduce the ?-Gorenstein cohomology
in terms of ?-Gprojective resolutions and ?-Ginjective coresolutions,
respectively, and then we get the balance of ?-Gorenstein cohomology.
Moreover, we study the interplay among ?-cohomology, ?-Gorenstein cohomology
and ?-complete cohomology, and obtain the Avramov-Martsinkovsky type exact
sequences in this setting.