سَلَّمْتُ عَلَى الْمُعَلِّمِينَ.
Translation: I greeted the teachers.
عَلَى: a preposition.
الْمُعَلِّمِينَ: genitive noun, marked by yāʾ.
Compare: «رَأَيْتُ الْمُعَلِّمِينَ» is accusative, but here the preposition requires the genitive. The visible ending is the same.
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Noun Case Classes: Type 6 — Sound Masculine Plural and Related Forms
سَلَّمْتُ عَلَى الْمُعَلِّمِينَ.
Translation: I greeted the teachers.
عَلَى: a preposition.
الْمُعَلِّمِينَ: genitive noun, marked by yāʾ.
Compare: «رَأَيْتُ الْمُعَلِّمِينَ» is accusative, but here the preposition requires the genitive. The visible ending is the same.