Please explain the mass$-$CV$,$ u$-$CV$,$ and v$-$CV for a staggered grid shown in the figure below, $.$e$.$g$.,$ mass conservation, approximating pressure, and velocities in different directions. $(10$ points$)$

Figure $2.$ Control volumes for a staggered grid: mass$-$CV $($left$),$ u$-$CV $($center$),$ and v$-$CV $($right$)$