In this post, I explain the use of the case marking system with sound masculine plurals. There are 2 endings that can be used with sound masculine plural nouns and adjectives, i.e. (ون) and (ين). In the nominative case, i.e. when the noun is used as the subject of a verbal sentence or as a subject or predicate of a nominal sentence, the first ending (ون) is used, e.g.

يعمل المهندسون المصريون في نفس الشركة.

“The Egyptian engineers work at the same company.”

المهندسون المصريون مجتهدون.

“Egyptian engineers are hard-working.”

When the noun is used as an object, the case is accusative and the ending (ين) is used, e.g.

قابلنا المهندسين المصريين.

“We met the Egyptian engineers.”

When the noun is used after a preposition or after the first word of an idaafa construction, the case is genitive and the ending (ين) is used, e.g.

تكلمت مع المهندسين المصريين.

“I spoke with the Egyptian engineers.”

شركة المهندسين كبيرة.

“The company of the engineers is big.”