My son was marked down for putting an apostrophe in the following sentence: 'Put that CD back in it's case over there'.
I always thought the apostrophe was put in to show the possessive - am I right please?
You are right, but that doesn't work with pronuns.
Let's see... you would say: It is my blanket and not it is I's blanket.
Interested in Language
It's = it is /it has