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.
جَرَيَ → جَرَى Past: heجَرَيَتْ → جَرَتْ Past: sheجَرَيُوا → جَرَوْا Past: they (m.)يَجْرِيُ → يَجْرِي Present: he