Comparison with the multiphase chemical evolution models of Mollá & Díaz (2005) for galaxies with different mass and star formation efficiencies. Left panels: models at the present time (T = 13 Gyr). Right panels: models at the epoch of PN formation (T = 8 Gyr). Each curve is for a given star formation efficiency. For each galaxy, we chose the most appropriate mass distribution indicated with N in the plots, where N is the designation of the model in Table 1 of Mollá & Díaz (2005).