阅读短文,回答下列问题。
Peter wanted to travel, especially to English-speaking countries such as America and Australia. But he knew that he had to improve his English, so he went to Green Language School to take English lessons. Peter worked very hard at his English. At last, he became ill. Every evening he went to bed, closed his eyes but he stayed awake(醒着的).
Peter was worried so he went to see the doctor." I can't sleep at night. What should I do, Doctor?"
"I have a piece of advice, "said the doctor. "Try to count(数)numbers. When you count up to 1,000, you'll be asleep."
The next day Peter returned to the doctor's office." Did you try my advice?And are you better today?" asked the doctor.
Peter wasn't happy. "Er, I tried counting from one, two...up to four hundred and twenty-one, and I felt sleepy. Then I got up and drank some coffee. Then I went on counting up to 1,000. But I still couldn't be asleep."