Question

أَيُّ means (which) and is always مضاف.The noun following it is مَجْرُور because it is مُضَاف إليه.

Accepted Answer

أيُّ طالبٍ خرجَ؟ (Which student went out?)- - -أيَّ كتابٍ قَرَأتَ؟ (Which book did you read?)- - -بِأَيِّ قَلَمٍ كَتَبْتَ؟ (Which pen did you write with?)Note: the word أيّ is مَرْفُوع in the first sentence because it is مُبْتَدَا, and it is مَنْصُوب in the second because it is مَفْعُول به, and مَجْرُور in the third because it preceded by the preposition بـِ

مَجْرُور أَيُّ Means مضاف Noun مُضَاف إليه أيُّ