Common mistakes
The second and third radicals are the same letter. They merge: رَدَّ: and come apart again before a consonant ending: رَدَدْتُ.
أَحْبَبَ → أَحَبَّ Past: heأَحْبَبَتْ → أَحَبَّتْ Past: sheأَحْبَبُوا → أَحَبُّوا Past: they (m.)يُحْبِبُ → يُحِبُّ Present: he