PV diagrams from the Crab across the north molecular cloud (see the routings shown in Figure 1). In each panel, the contours start at 3 σ and then increase in steps of 4 σ, where 1 σ in the large-field ¹²CO observations is roughly 0.25 K. The red rectangle in the bottom-right corner of each panel shows the angular (52″) and velocity (0.16 km s⁻¹) resolution in the MWISP ¹²CO observations.