Common mistakes
The root ends in و or ي, and the endings themselves change. Three patterns cover it: دَعَا يَدْعُو, رَمَى يَرْمِي and نَسِيَ يَنْسَى.
رَبَّيَ → رَبَّى Past: heرَبَّيَتْ → رَبَّتْ Past: sheرَبَّيُوا → رَبَّوْا Past: they (m.)يُرَبِّيُ → يُرَبِّي Present: he