THE POSSESSIVE FORM OF NOUNS
The possessive form is used with nouns referring to people, groups of people, countries, and animals. It shows a relationship of belonging between one thing and another. To form the possessive, add apostrophe + s to the noun.
-the book of Bill =Bill‘s book
-clothes for women = women’s clothes
For names ending in s, you can either add an apostrophe + s, or just an apostrophe. The first option is more common. When pronouncing a possessive name, we add the sound /z/ to the end of the name.
-James’ book will be published next week. /or James’s book will be published next month./
You’ll use this rule the most, so be sure to pay attention to it. Of course, English has some words that are plural but do not have an “s” at the end of them, like “children,” “sheep,” and “women.” These irregular plural words are treated as if they were singular words when making noun possessives. If a singular noun ends in “s,” you can either add an apostrophe + “s” to the end or just an apostrophe. Both are considered correct. The one you choose depends on how awkward the word sounds with an extra “s” on the end. “Mr. Roberts’ house” might sound better than “Mr. Roberts’s house,” but that’s a matter of opinion.
There are also some fixed expressions where the possessive form is used.
For example :
– a day’s work
– a month’s pay
– today’s newspaper
– in a year’s time
– For God’s sake! (= An oath of exasperation, annoyance, frustration or surprise )
– a stone’s throw away (= a short distance)
– at death’s door (= to be very sick)
-in your mind’s eye (= in your imagination or memory)