Comparison of the total molecular gas mass derived from the ¹²CO J = 1 − 0 and ¹³CO J = 1 − 0 lines for 23 galaxies in our sample. The dashed line represents the 1:1 ratio. Galaxies hosting extremely radio bright AGNs, which may significantly influence the measurements of radio flux density, are marked with a thick black circle, while those with radio bright AGNs, which are less likely to strongly affect the radio flux measurements, are marked with a thin black circle. These AGNs are labelled as ‘ERB’ and ‘RB,’ respectively, in the last column of Table 1 in Li et al. (2016a).