A young man worked very hard on his lessons. He was too busy to have a rest. One day he found that he couldn't fall asleep at night. As he became ill, he couldn't go to sleep. When he went to bed, he closed his eyes and tried to sleep. But he always failed. After a few days he decided to see a doctor. "I just can't go to sleep at night. What should I do?" he asked. "I have a suggestion," said the doctor. "You can try to count numbers. When you count to one thousand, you will be asleep. I am sure of it. " The next day the man returned to the doctor's office. "Well," said the doctor. "How are you today? Did you try my suggestion?" The man still looked tired. "Yes," he said. "I tried to count one, two, three.. , up to one thousand. But when I counted to five hundred and sixty--nine, I began to feel sleepy. I had to get up and drink some tea so that I could go on counting up to one thousand. But then I still couldn't fall asleep. " Why couldn't the young man go to sleep at night?
Because he didn't finish his lessons. Because he worked too hard. Because he was worried about his homework. Because there was a lot of noise.