Business English: A Practice Book by Rose Buhlig

3. To show the plural of letters, figures, and words that usually have

no plural; as, Your _3's_ are too much like your _5's_, your _a's_ like your _u's_. Don't use so many _and's_. Write sentences in each of which you use one of the following words correctly: you're we're who's they're your were whose there it's he's don't their its his doesn't Explain why the apostrophe is used in the following: