Common mistakes
The second and third radicals are the same letter. They merge: رَدَّ: and come apart again before a consonant ending: رَدَدْتُ.
مَرَرَ → مَرَّ Past: heمَرَرَتْ → مَرَّتْ Past: sheمَرَرُوا → مَرُّوا Past: they (m.)يَمْرُرُ → يَمُرُّ Present: he