POSSESSIVES
You are probably doing them wrong.
SINGULAR AND PLURAL NOUNS
To form the possessive of a singular noun (even if the noun ends in -s), add an apostrophe and an s.
The book’s ending made her angry. The empress’s palace was not very impressive. Mary’s house flooded last week. Professor Loibner-Waitkus’s class is a blast.
To form the possessive of a plural noun ending in -s, add only an apostrophe.
The players’ uniforms all stank. The firefighters’ truck caught on fire. The Joneses’ vacation turned into a nightmare.
To form the possesive of a noun that ends in -s in both the singular and plural form add an apostrophe.
She did not like her favorite television series’ ending. He only knew the species’ common name.
To form the possessive of an irregular plural noun not ending in -s, add an apostrophe and an s.
The children’s room was a mess. He considered majoring in women’s studies.
NOUNS EXPRESSING SHARED POSSESSION
To form the possessive of a noun in a series, add a single apostrophe and an s to the final noun if the ownership is shared. If the ownership is separate, place an apostrophe and an s after each noun.
Penn and Teller’s show was amazing. Mom’s and Dad’s cars are both in the shop.