Dust temperature vs. redshift of the high-z DSFGs in our sample, and DSFGs or LBGs from the literature. The dust temperatures of these sources are all measured with the optically thin modified blackbody model. The corresponding references are listed in the legend. We also overlaid the average T_dust-z relation of main-sequence galaxies derived by Schreiber et al. (2018) and Béthermin et al. (2015a) based on observational data. For HLS-4 with a photometric redshift alone, we show the degeneracy between dust temperature and redshift with the dash-dotted gray line. The T_dust of HLS-3 at the two possible redshifts is plotted and connected by the solid red line.