A young man works hard    1    his lessons. He is very busy   2    . He doesn't have time   3    . After
   4    , he falls ill. Every night, when he goes to bed, he    5    his eyes and tries to sleep. But he can't.
He thinks, "I must go to   6   the doctor." He tells the doctor, "I can't go to sleep at night." "Try counting(数)    7   . When you   8     1,000, you'll be asleep," says the doctor. The next day the man goes    9    
the doctor's office. "Well," says the doctor, "    10   are you today?" "Well," the man says, "I tried counting
one, two, three …up to 1,000.    11    when I reached 569, I began to feel sleepy (犯困的). I had to    12  
 and     13   some tea. Then I went    14    counting up to 1,000 again. But I    15   couldn't fall asleep."