Examples of multifrequency light curves of SN–CSM interaction. Our reference model ("cIIb/Ib/Ic," shown in red) is the one that fits to the spectra and light curves of SN cIIb 2011dh in cm wavelengths, where A _* = 4. The same model, with spectral flattening at γ = 200 and without it is shown by solid and dashed lines, respectively. We also examine models where only the CSM density is changed to A _* = 200 ("eIIb") and A _* = 50 ("cIIb–eIIb"). The 5σ detection limits in the continuum observation mode of ALMA with an exposure of 1 hr in each Band 3, 6, 7 are shown by dashed lines.