Needed to form possessive nouns and contradictions?

Contradictions are not Word forms; contradictions are a logical incompatibility between two or more propositions. Perhaps you meant the Word form, contractions.

Contractions and possessive nouns use an apostrophe.

A contraction is a shortened version of the written and spoken Words, made by replacing some of the letters with an apostrophe. Examples:

• The Words I am = I'm.
• The Words I will = I'll.
• The Words you are = you're.
• the Words you will = you'll.
• the Words could not = couldn't.
• the Words should not - shouldn't.

To form possessive nouns, an apostrophe s ('s) are added to the end of a Word; for some Words that already end with an s, just an apostrophe is added after the s at the end of the Word. Examples:

• The shoes of my mother = my mother'sshoes.
• The leaves of the tree = the tree'sleaves.
• The trunk of the elephant = the elephant'strunk.
• The traffic of the city = the city'straffic.