Mr. Jackson was a doctor in a small town. He was very absent-minded  . One afternoon, he went to visit a friend who lived not far from the town. They had dinner together and then talked and talked, for Mr. Jackson was very fond of talking. It was already midnight, then one o'clock, two o'clock and still Mr. Jackson kept on talking. But this time the friend was feeling very tired and kept looking at the clock on the wall. He didn't want to be impolite , but at last he said, "Charles, my dear friend, I don't want to put you out, but I have to go to work at six tomorrow morning, I must go to bed now. " "Oh, my God!" said Mr. Jackson in surprise. "I thought you were at my house. " Mr Jackson didn't leave his fiend's house because  _  .
he didn't want to leave his friend didn't want him to leave he thought he was at his own house he was too tired