Possessive Case

When we want to show that somebody owns something, we use the possessive, or the genitive case:

By the way, when one thing belongs to several people, we use the possessive form on the final name (Mary, Beth and Jane's room).

One more thing, when we talk about things, we use the 'of phrase' (the leg of the chair).

Now, watch this video to get the things right:

Try the exercises here or here.