Magnetoluminescence experiments in CdTe/CdMgTe single-quantum well with dense two-dimensional electron gases are performed at high magnetic fields up to 35 T. A broad photoluminescence peak, which originates in the Fermi edge singularity, evolves into singlet-charged excitons under the magnetic field in both sigma(+) and sigma(-) polarization. A triplet-charged exciton peak, however, appears only in the s- polarization, and the intensity of the triplet peak becomes intense above the magnetic field where the singlet peak of the s+ polarization crosses the triplet peak. The crossing magnetic field is consistent with the recent theoretical calculation of the magnetic field dependence of the charged excitons by Redlinski and Kossut, confirming that the nature of the PL peaks around nu = 1 can be explained from the viewpoint of the charged excitonic transitions even for the dense two-dimensional electron systems.