Common mistakes
The second and third radicals are the same letter. They merge: رَدَّ: and come apart again before a consonant ending: رَدَدْتُ.
حَلَلَ → حَلَّ Past: heحَلَلَتْ → حَلَّتْ Past: sheحَلَلُوا → حَلُّوا Past: they (m.)يَحْلُلُ → يَحُلُّ Present: he