Both ذَبَّ and عَلَّمَ contain shaddah, but for very different structural reasons.
ExampleRootWhy shaddah appears
ذَبَّذ ب بIdentical second and third radicals
عَلَّمَع ل مDerived Form II pattern
تَعَلَّمَع ل مDerived Form V pattern
مَدَّم د دDoubled triliteral root
Do not equate shaddah with Form II. An attached suffix can expose both underlying consonants, as in مَدَدْتُ.
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Advanced Sarf Application: Ambiguous Forms, Weak-Letter Reasoning and Error Correction
Both ذَبَّ and عَلَّمَ contain shaddah, but for very different structural reasons.
ExampleRootWhy shaddah appears
ذَبَّذ ب بIdentical second and third radicals
عَلَّمَع ل مDerived Form II pattern
تَعَلَّمَع ل مDerived Form V pattern
مَدَّم د دDoubled triliteral root
Do not equate shaddah with Form II. An attached suffix can expose both underlying consonants, as in مَدَدْتُ.