ضَرَبَ — يَضْرِبُ
He struck — he strikes.
Here the second radical rāʾ has kasrah. When the initial يَ is replaced by مَ, that kasrah is retained. The result is مَضْرِبٌ, not maḍrab.
يَضْرِبُ ← مَضْرِبٌ
This example makes clear why a mafʿil pattern can result from a kasrah-bearing imperfect stem.
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Deriving مَضْرِبٌ from يَضْرِبُ
Ism al-Ẓarf: Meaning, Patterns, Paradigm and Derivation
ضَرَبَ — يَضْرِبُ
He struck — he strikes.
Here the second radical rāʾ has kasrah. When the initial يَ is replaced by مَ, that kasrah is retained. The result is مَضْرِبٌ, not maḍrab.
يَضْرِبُ ← مَضْرِبٌ
This example makes clear why a mafʿil pattern can result from a kasrah-bearing imperfect stem.