Do not memorize the active table as 14 unrelated forms.
Look for the three familiar Lam effects:
ExampleEffectForms
لَمْ يَفْعُلْfinal Dhammah → Sukoon5
لَمْ يَفْعُلَاNoon-e-I'raabi drops7
لَمْ يَفْعُلْنَvisible form unchanged2
Once you recognize the group, the form becomes easier to predict.
Opening interactive controls...
Conjugating Past Absolute Negation with "Lam" (Active & Passive)
Do not memorize the active table as 14 unrelated forms.
Look for the three familiar Lam effects:
ExampleEffectForms
لَمْ يَفْعُلْfinal Dhammah → Sukoon5
لَمْ يَفْعُلَاNoon-e-I'raabi drops7
لَمْ يَفْعُلْنَvisible form unchanged2
Once you recognize the group, the form becomes easier to predict.