From top to bottom: a) average spectrum of 33 quiescent galaxies in the GMASS sample; b) average spectrum of mixed galaxies in the [OII] sample, at 1 <z< 1.6; c) average spectrum of not-mixed SFGs in the [OII] sample, at 1 <z< 1.6. Mixed galaxies have high values of the three continuum indices indicated by grey shaded regions: MgUV (2600−2900 Å) (Daddi et al. 2005); C(29−33) (2900−3300 Å) (Cimatti et al. 2008); D4000 break (3750−4250 Å) (Bruzual A. 1983). See the text and Fig. 4 for more details.