新概念英语mp3听力下载第二册lesson 81

First listen and then answer the question.
Why did the prisoner attack the driver?

    When he had killed the guard, the prisoner of war quickly dragged him into the bushes. Working rapidly in the darkness, he soon changed into the dead man's clothes. Now, dressed in a blue uniform and with a rifle over his shoulder, the prisoner marched boldly up and down in front of the camp. He could hear shouting in the camp itself. Lights were blazing and men were running here and there: they had just discovered that a prisoner had escaped. At that moment, a large black car with four officers inside it, stopped at the camp gates. The officers got out and the prisoner stood to attention and saluted as they passed. When they had gone, the driver of the car came towards him. The man obviously wanted to talk. He was rather elderly with grey hair and clear blue eyes. The prisoner felt sorry for him, but there was nothing else he could do. As the man came near, the prisoner knocked him to the ground with a sharp blow. Then, jumping into the car, he drove off as quickly as he could.