Ann: How about pasta with chicken in tomato sauce for dinner tonight?
Bob: That sounds great! Have we got everything we need?
Ann: Let's look in the cupboard.
Bob: We've got a lot of onions, but there isn't any garlic.
Ann: Is there any cheese?
Bob: There is some, but there isn't any chicken. And there isn't much olive oil.
Ann: OK, let's make a shopping list, then.