Mr. Black's eyesight is too bad, but he doesn't like wearing glasses. One day, after climbing the mountain s in the day, Mr. Black was very tired at night, he stayed in a hotel room with a bottle of wine in each hand. On the wall there was a fly(苍蝇), but he thought it was a nail(钉子). So the moment he hung them on, the bottles fell broken and the wine spilt all over the floor. When a waitress found what had happened, she decided to help him.
So the next morning when Mr. Black was taking a walk in the garden outside the hotel, the waitress put a nail in the place where the fly had stayed.
Then Mr. Black came into his room. When he looked up at the wall, he found the fly was there again! He walked to it carefully and slapped it. On hearing a loud cry, the waitress came in quickly. To her great surprise, the poor old man was there sitting on the floor, with his right hand bleeding!