Lakhasly

This four-form paradigm is maximal, and not all nouns have all the four forms. Many nouns do not take the possessive forms, since an of structure often takes the place of the {-s ps) morpheme.If, for instance, you were to hear /da daktarz semmar/, it could mean "the doctor's seminar," "the doctors' seminar," or "the doctors seminar."

This four-form paradigm is maximal, and not all nouns have all the four forms. Many nouns do not take the possessive forms, since an of structure often takes the place of the {-s ps) morpheme. For example, one is more likely to say "the ceiling of the room" than "the room's ceiling." In the spoken language we cannot always be sure which s morpheme we are hear-ing, because the possessive and the plural have identical forms /-5/, /-7/, and /-az/-except in the case of irregular plurals. If, for instance, you were to hear /da daktarz semmar/, it could mean "the doctor's seminar,"
"the doctors' seminar," or "the doctors seminar."
A few groups of so-called nouns have only one form of this paradigm.
The words in one group--like tennis, courage, and haste- have the form of the stem. Another group does not have a singular form but only that of the -s plural: clothes, environs, trousers, and others. These take they/them as a pronoun substitute and go with the plural form of the verb, e.g., "My clothes [they] are clean." Still another group ends in an -s, words like economics, linguistics, mathematics, physics, but these take it as a pronoun substitute and go with a singular form of the verb, e.g., "Linguistics [it] is an exacting discipline." Words in a certain ill-defined group end in -S, like ethics, oats, pliers, suds, measles, but may be either singular or plural, depending on the context in which they occur or on the meaning expressed.