Selection of the 騯 genitive can be described in relation to the gender classes represented by the noun which takes the 騯 suffix. The genitive is not used with all nouns equally but tends to be associated with those of animate gender, especially with those having personal reference. Although we can say either the youngest children´s toys or the toys of the youngest children, the two forms are not generally in free variation. We cannot say, for example, the *roof´s cost or *the hat of John. Thus, nouns denoting persons, whether proper names or ordinary count nouns, can always take the inflected genitive. It can also be used with animals. The rule of the thumb here is that the higher animals are more likely to have the 騯 genitive than the lower animals.

The following four animate classes normally take the genitive:

Personal names: Washington´s statue, Segovia´s pupil, Gonzalez´s speech.

Personal nouns: the boy´s new shirt, My mother´s necklace, my sister-in-law´s pen.

Animal nouns (specially higher animals): the horse´s neck, the farm dog´s bark, the lion´s tail, the tiguer´s stripes.

Collective nouns (organizations): the committee´s decision, the nation´s resources.

The inflected genitive is also used with certain kinds of inanimate nouns:

Geographical names: especially if followed by a superlative adjective, with only and with general ordinals. E.g: the world´s best universities, The country´s only university, African´s first art festival (taken to mean a group of people).

More generally, genitive combines with them to express a relative clause meaning: The Cabinet´s greatest mistake (=the greatest mistake the cabinet made); Europe´s future; Harvard´s department of linguistics.

Locative nouns: locative nouns denote regions, heavenly bodies, institutions, etc They can be very similar to geographical names, and are often written with initial capital letters. E.g: the Earth´s interior, the Church´s mission, the hotel´s ent, the nation´s chief, a country´s population, the school´s history.

Temporal measure and value names: A week´s holiday; At four hundred yard´s distance; a day´s work; a moment´s thought

Nouns of special relevance to human activity: In freedom´s name; duty´s call, the poll´s result; television´s future; my life´s aim; in freedom´s name; love´s spirit.

So, it could be said that the possessive case is chiefly used with people, countries or animals, as shown above, but it can also be used:

Of ships and boats: the ship´s bell, the yatch´s mast.

Of planes, trains, cars and other vehicles, though here the 鰂f-construction� is safer. E.g: A glider´s wing / the wings of a glider.

In time expressions: a week´s holiday, in two year´s time, ten minutes´break.

In expressions with money + worth: then dollars´worth of ice-cream.

For + noun + shake: for heaven´s shake.

In a few expressions, such as: a stone´s throw, journey´s end, water´s edge.

 We can say either 鬭 winter´s day� or a winter day and a 鷔ummer´s day� or 鬭 summer day�, but we cannot make spring or autumn possessive.