some dogs are trained to scratch at the door when they want to go outside
dogs is not barking_at_strangers. rescue_dog is not police_dog. outside_dog is not dog. arson_dog is not police_dog. bomb_sniffing_dog is not dog. pet_door is not door. dogs is barking_at_strangers. bomb_sniffing_dog is dog. outside_dog is dog. police_dog is working_dog.