Complex sentence: The last of these were retired in 2002, replaced by "MiG-21 Lancer A" s. Eleven "MiG-21R" s, locally designated "MiG-21C" ("Cercetare") were delivered in 1968, remaining in service until 1998.
Split into simpler sentences: The last of these were retired in 2002, replaced by MiG-21 Lancer As. Eleven MiG-21Rs, locally designated MiG-21C ("Cercetare") were delivered in 1968, remaining in service until 1998.