D

    John was a very strong man. Once he got a job of cutting wood in a forest. His boss gave him an axe(斧子) and showed him the area where he should work.

    The first day, John cut down 18 trees. "Good," the boss said, "keep it up!" John was encouraged by the words of the boss and tried harder the next day, but he could only cut down 15 trees. The third day he tried even harder, but he could only cut down 10 trees. Day after day he was cutting down fewer and fewer trees.

    "I must be losing my strength," John thought. He went to the boss and said that he could not understand what was going on. "When was the last time you had sharpened(使锋利) your axe?" the boss asked. "Sharpened? I had no time to do it. I have been very busy trying to cut more trees." said John.

    While John was working hard, he didn't think about how to do his job better.

    One day an American was in Africa. He wanted to go to a small village in the hill. He got on a bus and the driver said: "The yellow ticket is one dollar. I have two other tickets. The red one is fifty cents, and the green, ten cents." "A green one, please "said the man. The bus started to get up the hill. Suddenly it stopped. "Red ticket passengers, get out and walk. Green ticket passengers, get out, close the door, and push the bus." shouted the driver.