The normal pattern for a sound, unaugmented triliteral is مَفْعُولٌ. The placeholders f-ʿ-l are replaced by the three root letters, while the pattern contributes the prefix mīm and long ū.
Word / formMeaning / explanation
نَصَرَ ← مَنْصُورٌhelped.
ضَرَبَ ← مَضْرُوبٌstruck.
سَمِعَ ← مَسْمُوعٌheard.
This is the regular sound-triliteral rule. Verbs with weak radicals may undergo further morphological changes.