In this lesson we will Insha Allah learn a new word أَيُّ and the rules for its use. أَيُّ  is an interrogative article - i.e. it is used to ask questions.  In Lesson No. 4 section 4 we have already learnt the use of some of the interrogative articles. However unlike the other interrogative articles, أَيُّ  meaning "which" is used as a Mudaf (possessed), so any word that follows أَيُّ will be treated as Mudaf Ilaihi therefore it will take the genitive case (with a kasratain).

e.g., أَيُّ بَيْتٍ هَذَا  means "which house is this?".

However the word أَيُّ  will take different cases in different situations e.g.,

• أَيُّ will take a nominative case (with a damma), if it appears as مُبْتَدَأَ - i.e. in a nominal sentence, for example:  أَيُّ مَدْرَسَةٍ هَذَا؟  means which school is this?, 

• أَيُّ will take a genitive case (with a kasra), if it is preceded by a preposition e.g.,
   فِي أَيِّ غُرْفَةٍ دَخَلْتَ؟  means in which room did you enter?, and

• أَيُّ will take an accusative case (with a fatha), if it appears as مَفْعُوْلٌ (the object of a verbal sentence) e.g., تُحِبُّ أَيَّ لُغَةٍ؟ it means which language do you like?

Lets take some more examples of this rule: