be selected as LAEs in a narrow band survey. The rest of the   have a line emission too faint to pass that selection. Lyman break galaxies with no sign of emission or with a clear absorption are called $LBG_N$ and are also 66 (note that two galaxies show both a clear emission line and an absorption and are included in both samples). The two sub-samples are not biased in terms of V-band magnitude, or absolute rest-frame luminosity at 1400Å (see first entry of Table 1). This indicates that, for this sample, the redshift confirmation of LBGs does not depend sensibly on the presence of emission lines (see also Popesso et al. 2009). In Figure 1 we plot the redshift distribution of our final sample of galaxies, as well as for the two sub-samples separately. The overall redshift distribution of our LBGs, and in particular the partial lack of objects around z$\sim 3$, is shaped by the spectroscopic completeness level of the GOODS catalog (plotted in Figure 6 of Popesso et al. 2009). This spectroscopic catalog is actually formed by a compilation of many different spectroscopic surveys (as discussed earlier), each with its own selection criteria and efficiency: the completeness level 