I've got tickets for the film of Romeo and Juliet tonight. Do you want to come?
Oh, er, well actually...
You don't have to come if you don't want to. You can stay in and write your essay on insects if you prefer!
No, it isn't that, but you see I've to help organize Jill's party tonight so I'm afraid I can't come to the show. Tell you what I thought? Why don't you come to the party instead?
Can I? Do you think Jill would mind if I did?
No. I'm sure she wouldn't. You have to bring a bottle of course, but it doesn't have to be expensive.