We study effects of cosmic fluids on finite-time future singularities in
modified f(R,G)-gravity, where R and G are the Ricci scalar and the
Gauss-Bonnet invariant, respectively. We consider the fluid equation of state
in the general form, ω=ω(ρ), and we suppose the existence of a
bulk viscosity. We investigate quintessence region (ω>−1) and phantom
region (ω<−1) and the possibility to change or avoid the singularities
in f(R,G)-gravity. Finally, we study the inclusion of quantum effects in
large curvatures regime.Comment: 14 page