A Bookshelf or Something Else？

We spent a day in the country and picked a lot of flowers. Our car was full of flowers inside! On the way home, we had to stop at traffic lights, and there my wife saw the bookshelf. It stood outside a furniture(家具) shop. “Buy it ,” she said at once. “We‘ll carry it home on the roof rack(车顶架). I‘ve always wanted one like that.” What could I do‘?. Ten minutes later I was twenty dollars poorer, and the bookshelf was tied on to the roof rack.