Integrated line ratios of formamide (pink stars) and methyl cyanide (black circles) to methanol for the fiducial models and those with high-millimeter opacity dust. The lines of formamide, methanol, and methyl cyanide are the same as those in Fig. 3. The empty symbols show the models with disks. The considered lines in the low-mass model with disk and high-millimeter opacity dust are not detected and hence there are no measurements. The scatter in NH₂CHO/${\mathrm{C}\mathrm{H}}_3^{18}\mathrm{O}\mathrm{H}$ (pink stars) is larger than that in ¹³CH₃CN/${\mathrm{C}\mathrm{H}}_3^{18}\mathrm{O}\mathrm{H}$ (black circles).