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.
رَمَيَ → رَمَى Past: heرَمَيَتْ → رَمَتْ Past: sheرَمَيُوا → رَمَوْا Past: they (m.)يَرْمِيُ → يَرْمِي Present: he