Case indicates the relations of the noun ( or pronoun ) to the other words in the sentence. Nouns denoting living beings and some nouns denoting lifeless things have two cases:
the common case.
the genitive case.
The genitive case is formed by:
‘s – is used with the singular and plural nouns not ending in –s:
a man’s job, men’s job, a child’s voice, a children’s voice.
b) a simple apostrophe (‘)is used with plural nouns ending in –s: the students’ hostel, the Smiths’ car.
other names ending I –s can take “ ’s ” or the “ ’ ” alone:
