(3) Steady-state approximation is usually applicable but not always applicable. For the mechanism above, in which one of the following cases, we may NOT use steady-state approximation? Please circle it. ( 5 pts )
(i) \( k_{-1} \gg k_{1} \) and \( k_{2} \gg k_{1} \)
(ii) \( k_{1} \gg k_{-1} \) and \( k_{1} \gg k_{2} \)