Choose the correct instrumental form — with whom (sa), with what tool, and by what transport.
Masculine & neuter: grad → gradom, selo → selom (after č/ž/š/j often -em: ključ → ključem, nož → nožem) · Feminine: žena → ženom · consonant feminines: radost → radošću.
Three great uses: sa/s + instrumental (sa sestrom), the tool (nožem, olovkom), and transport (vozom, autom). Prepositions of position pred, za, nad, pod, među also take the instrumental.