orientations leads to a complete breaking for the parameter degeneracy. Thus, the constraints from the combination of E-ELT and SKA (SKA1 or SKA2) would have a tremendous improvement, as shown by the gray and red contours in Fig. \[ELTvsSKA\]. This may be due to the fact that the experiments of the E-ELT and the SKA are complementary in mapping the expansion history of the universe with a model-independent way. That is to say, these two experiments will be able to directly perform reconstruction of the expansion history of the universe in the dark matter- or dark energy-dominated epochs by using different observational techniques. Particularly, the result from the combination of E-ELT+SKA2 is almost as good as the constraint from the combination of SN+CMB+BAO, which implies that the redshift drift observation would have chance to be one of the most competitive cosmological probes.

Meanwhile, we find that the degeneracy orientation of E-ELT+SKA1 or E-ELT+SKA2 in the parameter plane is evidently different from result for the combination of SN+CMB+BAO. This phenomenon would result in an effective breaking of the parameter degeneracy and a significant improvement of the constraints on dark energy. It is of extreme interest to know what role the redshift 