A young woman was driving through the lonely countryside. It was dark and raining. Suddenly she saw an old woman by the side of the road, holding her hand out as if she wanted a lift. 'I can't leave her out in this weather', the woman said to herself, so she stopped the car and opened the door. 'Do you want a lift?' she asked. The old woman nodded and climbed into the car. After a while, she said to the old woman, 'Have you been waiting for a long time?' The old woman shook her head, 'Strange', thought the young woman. She tried again. 'Bad weather for the time of year', she said. The old woman nodded. No matter what the young woman said, the hitchhiker(搭便车的人) gave no answer except for a nod of the head or shrug(耸肩). Then the young woman noticed the hitchhiker's hands, which were large and hairy. Suddenly she realized that the hitchhiker was actually a man. She stopped the car. 'I can't see out of the rear-screen', she said. 'Would you mind clearing it for me?' The hitchhiker nodded and opened the door. As soon as the hitchhiker was out of the car, the terrified young woman raced off. When she got to the next village she pulled up. She noticed that the hitchhiker had left his handbag behind. She picked it up and opened it. She gave a gasp(喘息)—inside the bag was a gun. The woman stopped the car because ______.