Possessives

You can see how the basic possessive is formed in these examples:

        1.  John's car is new.  (add -'s to a singular noun)
        2.  The boys' mother is young. (place -' after the -s
                   of a plural noun)

If a singular noun ends with an -s, we usually add -'s to make it possessive:

        3.  Bess's teacher is Scottish.

But sometimes this sounds funny, so we just add -' after the final -s:

        4.  Jenkins' writing class is confusing.

Sometimes we prefer the structure "noun+of+noun":

        5.  The cost of the operation was extremely high.

Sometimes we use a noun as an adjective rather than a possessive:

        6.  *The students' center is new.  (possessive sounds funny)
        7.   The student center is new. (noun as attribute, i.e. adjective)

Finally, be careful not to confuse the possessive with the plural, or with a contraction:

        8.  The boys went to the swimming pool.  (plural, not
             possessive)

        9.  John's working late tonight.  (contraction of "John is")

For more complete explanations and exercises, go to these links:

Links:

        Explanation and exercise:  apost.html         
          Exercise, possessive and plurals:  more possessives and plurals
          Another exercise:  possplu.htm