Projected rotational velocities of different stellar groups, defined based on the CMD (see Fig. 8). Top four panels: from top to bottom, the panels show the v sin i distributions of star in the MS region, the TO region, the BSS region and the Be star region. In each panel, the detected SB1s are marked by a darker color, as indicated in the legend. Bottom panel: normalized cumulative distribution of the rotation rates of different groups, as indicated in the legend.