A: Did you wipe your feet? B: Yes, of course I wiped my feet. A: Then why is there mud on the carpet? B: I don't know. It's not my mud. A: Well, someone brought it into the house. B: Look at the bottom of my shoes—they're clean. A: Of course they're clean. You left all the mud on the carpet. B: Okay, I'll get the vacuum cleaner. A: Don't vacuum it now. B: Don't you want me to clean up the mud? A: Wait till it dries. It will be easier to vacuum. B: Next time I will be more careful.