Position-velocity diagrams for [C ii], CO(2–1) and H i along the north-south (top) and east-west (bottom) directions in the central region of M 33. The contours in the middle and right panels correspond to [C ii] emission and range from 10% to 100% of the peak values of 0.6 and 0.8 K in steps of 10% for the NS and EW cuts, respectively. The color bar on top of each panel shows the color scale of the corresponding image in units of K. The crosses in all panels denote the nominal velocities due to galactic rotation obtained from H i spectra (see text).