دستورِ زبانِ پارسی

The selective pronoun is a nominal pronoun which represents a single element of a set, which is definite, however, when it has not yet been determined by speech which element is meant.

In Persian, the numeral phrase /jek kodɒm/ یک کدام (= [_NP[_DetPcardinal numeral /jek/ یک] [_NPinterrogative pronoun /kodɒm/ کدام]]) is used as selective pronoun.

The following points should be noted about the selective pronoun:

1. It is always indefinite.
2. It is always in the 3^rd person.
3. It is always in the singular.

Although the selective pronoun is always in the 3^rd person singular, the predicate conforms to the number and the person of the superset and can cause a verbal discord in the number and in the person (see 3•۱•b. and 3•۳•b.):

یک کدام به مادرتان کمک کنید (۲^nd person plural)!

یک کدام جانشینِ آقایِ رییس می‌شویم (۱^st person plural).

The predicate can be used concordingly (in the 3^rd person singular), provided that the person of the superset has been determined (see 7•۸•b. and 7•۱۰•b.):

یک کدام از شما به مادرتان کمک کند!

از ما کارمندانِ قدیمی یک کدام جانشینِ آقایِ رییس می‌شود.

The selective pronoun can become formation base of partitive genitive phrases and occur with modifiers, which are in the plural (see 10•۴•d•a. and 10•۴•d•b.):

یک کدامِ شما /jek kodɒm-e ʃomɒ/ به مادرتان کمک کند!