Articles agree in number to the noun they specify. The values
singular and plural are pertinent to the class. Note that this
last value does not apply in presence of the value indf (see
below).
The value invariant shared by nouns and adjectives, which
identifies an underspecification in number, is not pertinent to
articles. The article specifies the number (but see the familiar and
dialectal use l'attenzioni) and, for this reason, it can be
used in context to solve the
underspecification of nouns and adjectives: le pari
opportunita', una pari opportunita'.