NOT OPEN / DOOR / UNLESS / YOU / SURE / WHO / VISITOR / BE.A. NOT...
80. not open / door / unless / you / sure / who / visitor / be.A. Not open the door unless you are sure who is the visitor. B. Unless you are sure who is the visitor, don't open the door. C.Your are not sure who the visitor is, unless you open the door.D. Don't open the door unless you are sure who the visitor is. ---THE END---