  An NUV-optical diagram made for sources from the secend Galaxy Evolution
Explorer (GALEX) Ultraviolet Variability (GUVV-2) Catalog provide us a method
to tentatively classify the unknown GUVV2 sources by their NUV-optical
magnitudes. On the purpose of testing the correctness and generality of the
method, we carry out a program on the spectroscopic observations of the
unidentified GUVV2 sources. The spectroscopic identification for these 37
sources are 19 type -A to -F stars, 10 type -G to -K stars and 7 M dwarf stars
together with an AGN. We also present the light curves in R-band for two RR
Lyrae star candidates selected from the NUV-optical diagram, both of which
perform cyclic variations. Combining there light curves and colors, we classify
them as RR Lyrae stars. To confirm the results, we shows a color-color diagram
for the 37 newly spectroscopically identified objects compared with the
previously identified ones, which manifests good consistence with our former
results, indicating that the ultroviolet variable sources can be initially
classified by their NUV/optical color-color diagram.

Solar and Stellar Astrophysics;Astrophysics of Galaxies