Question

Interrogative nouns like من، ما، كم are indefinite when they are مبتدأ.

Accepted Answer

ما بِكَ؟ (What is wrong with you?), where ما is the (mubtada) and prepositional phrase بِكَ is the (khabar).- - -مَنْ مريضٌ؟ (Who is sick?)

Text	Interrogative nouns like من، ما، كم are indefinite when they are مبتدأ.
Back Extra	ما بِكَ؟ (What is wrong with you?), where ما is the (mubtada) and prepositional phrase بِكَ is the (khabar). - - - مَنْ مريضٌ؟ (Who is sick?)

ما Interrogative Nouns من كم Indefinite مبتدأ بِكَ